I used to do this years ago and still do occasionally. What works best for me is splitting the whole bottle in half as soon as I get it. I put half of it in an older vial and write the date on it for whenever two weeks would be, and don't touch them until that date.

This way you can still go hard but you have a better idea of how hard you're going, and if you run out of the first half in a week or so, you only have 4-7 days off instead of the grueling 14.

I think lots of people take it this way. I'm basically non functioning without at least a little adderall. What also helps is breaking up all my pills (I get 2 20mg IR per day but my dose schedule is 10,20,10 on most days) into halfs ahead of time. I've noticed I get just as much hyperfocus with 10 as with 20, and even 5mg registers enough to get me going, so it helps that I have 120 half-tablets (or 240 quarter tablets) instead of 60 full ones.