I see variations of these questions all the time and figured I'd address them. The answer to these questions and all their variations is very simple.

If you need to "game" your schedule to have time away from girls, play "hard to get", or intentionally "appear uninterested", you need to do more with your life.

I'll elaborate.

If your schedule is so flexible that you can see someone and go on dates at any time during any night of the week, and thus have to figure out some kind of algorithms for "how often is too often", you probably aren't doing many things and should start to get out more. If you have a busy schedule but you're willing to drop or change it simply to go out with her, you're too invested and demonstrating insecurity. Girls say that they want to be treated like a princess and want guys who will pick them up at the drop of a hat, but when we look at reality, all of those guys are friendzoned. (It should be obvious that if you're in a relationship and there is some kind of actual emergency, exceptions can be made).

Girls are attracted to men who live interesting lives, and if you tell her you can't go out because you already have plans, and she is a quality woman, this will be received positively. If a girl tries to make you cancel plans or stop going out or doing hobbies just to spend time with her, she is demonstrating neediness and insecurity. Why would you want to be with a woman who doesn't respect your lifestyle?

Onward!

Playing "hard to get" or "appearing uninterested" can and does work, but you're going about it for the wrong reasons. The reason that "playing hard to get" and "appearing uninterested" works on girls is that it makes you look less invested in her than you are in yourself, and that is very attractive. (Credit to "Models" for this). This is not a good thing, though, if you're "gaming" it and not legitimately more invested in yourself than you are in her. If you are highly invested in a woman's opinion of you, but you "play hard to get" or "appear uninterested", you're performing rather than being authentic in those regards. This may work in the short run, but pretty soon she'll realize that you're actually more invested in her and you'll become less attractive.

How can we fix this?

Live a more interesting life, invest more in yourself than you do in the opinions of others, and meet more girls. You won't need to play "hard to get" if you are legitimately out doing interesting things and talking to other women; you'll actually be hard to get, and she'll chase you without you needing to perform.