Deadlines? Imagine you have an important exam/audition in two days, but haven't had the time to study/rehearse properly. Then, tomorrow you look yourself in the chamber with your books/instrument and leave it when you're totally awesome. OTOH, since (IIRC) you are only allowed into the chamber twice in your life (and even if this weren't the case, you don't want to be 35 subjective years old 25 calendar years after the date on our birth certificate), you only do that for things you really care about.
Deadlines like that are zero-sum games, and so the impact is limited - it shifts around who wins the exams/auditions at a substantial cost (whatever it takes to use the HTC over just living in the real world). On the macro scale, I'm not sure how much it matters at the margin: if someone needs a HTC just to study for an exam...
Master version on gwern.net