Should you exhaust every number you get until "the ho says no", or should you play it cool and next girls as if they were disposable, if they don't seem to be biting whatever bait you throw them? This has always been a big point of contention in the PUAworld, and I am here to settle it once and for all by laying down the definitive answer.
It really depends on your level of talent and proficiency, and even on your circumstances.
When I was a beginner, I would not let a number go until it was exceedingly clear that it wasn't going anywhere. When I reached intermediate level I would use occasional light pinging to gauge interest, and if interest was lacking I would delete numbers, unless it was a 8-10 girl for me, in which case I'd keep it going in one way or another for ages. And now that I am the best in the world at this stuff... I simply do whatever the fuck I feel like doing at any given moment, completely freeform, without thinking about it twice or doubting or second-guessing myself in any way. Females are disposable (and if you disagree it means you are sexually inexperienced and/or have an ugly girlfriend or wife who therefore isn't very female, and/or you're somewhat of a female yourself) and therefore putting too much thought or effort into them is an utter waste of time, and gives inferior results to boot, so no truly advanced PUA ever does that. Going completely freeform on them then, without spending a second thinking about past interactions—not even on what happened five minutes ago—is how the advanced PUA expresses this mindset and, let's face it, this contempt towards the female species. Because contempt is where the man will always arrive when he gains enough experience of the free female to truly understand her. Even females agree with this; no one is more contemptuous of females than females themselves; men have to LEARN this contempt, but females are born with it. That's why they worship males. (And that's why they hate the pseudo-males that worship females.)
That doesn't mean that a beginner should try to employ the advanced method. That would be a recipe for failure, even for naturals who, despite their super-fast progression, still need to go through all the stages of advancement, albeit far more quickly. To the beginner, therefore, a phone number is precious because he has sweated like a pig to overcome his approach anxiety to get it, and he only has a few of those at any given time, if he has any of them at all. It is therefore the natural thing to do in his case to exhaust the number in any number of ways, whether that is wearing it down with daily messages until the ho says no, or tactically pinging it at mathematically calculated intervals in an attempt to avoid appearing as desperate as he obviously is. My advice to beginners therefore is: try everything, and fail at everything as much and as quickly as possible. Eventually, you'll figure out what works, and you'll progress to the intermediate stage. That stage is when you have experienced "texting hell" enough to know that you don't want it in your life, and therefore any female that brings it in should be discarded like the piece of rubbish that she is. But you have to thoroughly experience it first to learn that even celibacy is preferable to it, so text away to your heart's content, dear beginners, and enjoy the process, because it IS enjoyable, especially to those talented enough and determined enough to one day become decent at this stuff (obviously the ones who will fail and quit won't have enjoyed it, because otherwise they wouldn't have quit).
The intermediate stage brings with it a level of maturity that will allow itself the luxury of deleting numbers, basically due to disgust with those girls' reactions, which are indeed often disgusting. Ghosting, for example, is a disgusting habit. To the intermediate player, it feels humiliating to keep texting a girl who's ghosted him, so he will generally avoid doing it. At the same time, he has to learn the psychology of ghosting, and understand why girls do it so much. It's not that they are trying to humiliate you—the humiliation is entirely in your mind, while in their minds there's nothing quite simply because they're not thinking about you at all. They DON'T CARE ABOUT YOU, and therefore don't want to have to think about you at all. It is awkward and uncomfortable to them to deal with you at that stage, because they obviously don't like you while you like them a lot, and they just can't bring themselves to tell you that they don't like you. It's far easier for them to simply ignore you, and therefore that's what they do, because weak people always take the easier option to everything. Consider my behavior, in contrast. I don't think I've ever ghosted anyone, including girls I've wanted to get rid of. It is unpleasant rebuffing their endless advances, and it is even more unpleasant doing so while trying to protect their ego, yet I still do it because I don't enjoy hurting these girls who've never hurt me but on the contrary even stroke my ego with their attentions. It would be cruel of me to tell them the truth, the truth being "You're only a 7, and I can get 10s when I put my mind to it, so there's no way in hell I am gonna give you more than some dick when I just happen to not have anything better available". I've never said anything like this to anyone, and I'd almost rather die than say it—hence I lie and make up reasons such as "I am not looking for a girlfriend right now" (which is a lie since I am always looking), or "I am too busy with work", or "We'd be better off as friends", and so on: you know, the exact same excuses girls give guys when they have not yet reached the stage of ghosting you, which, if you keep pushing them, they eventually will. So instead of taking that negatively, take that positively for once: these are girls that are NICE ENOUGH TO LIE TO YOU, because they still care, to some extent, about your feelings. So accept their lie graciously and move on. Or would you rather they ghosted you instead, pretending you don't even exist? Take the ghosting as an indication that you were dealing with a HORRIBLE SUBHUMAN BEING, and count your blessings that you did not end up involved with her, or that whatever involvement you may have had is thankfully done, AND MOVE THE FUCK ON.
And finally, if you're gifted enough and determined enough, you reach the advanced stage. By this point you will have had enough experience with females—sexually and socially—to know exactly how their minds work, which is not at all. They can barely be said to be alive/conscious, and their reactions are more robotic than anything else, and hilariously simplistic and transparent in the bargain; the advanced player can almost see the gears turning in girls' heads when they are evaluating circumstances and suitors, and it is a base and disgusting process. The less said about it, therefore, the better, is what the advanced player believes. He doesn't want to even have to THINK about females at all, he just wants to look at them, because unlike men all their beauty is on the outside, where God intended it to be (and by God I mean me). Men like me have so much depth inside them that, when we look at women, we want precisely the opposite of that: and everyone who desires females with depth is himself somewhat of a female, and thus shallow. That's why he's looking for depth outside of him, because he doesn't have much. Let him look for it then—but he will never be a good PUA, because girls are not attracted to girls, they are attracted to men, and the effeminate PUA is no man, and the girls know it. The advanced PUA is a man who through sheer talent and effort has reached the stage of fully understanding women, and properly valuing them for what they are good at: their looks, their shallowness, their silliness and playfulness that is the ideal antidote to a serious life spent in serious pursuits. Women, the way the advanced PUA treats them, are merely another type of videogame, "the sexual scenario" as Baudrillard put it, and pick-up art has finally truly become a GAME for these people, a game so enjoyable and addictive that they are loath to abandon it even when they have settled down and become family men, which is why many of them don't, with old-style womanizers like Taki still hitting on females well into their '80s, and proud of it, not even trying to hide it from their wives and children anymore, if they ever did. And of course, there's no question at that level of strategizing and agonizing over numbers or individuals any more than a videogame player agonizes over the loss of any given "life". Those people really believe that "it's just a game" in the end, so of course nothing you do in it really matters, which ironically is precisely the optimal mindset to have if you want to achieve results that really do matter, and can change your life.