I almost always book tickets for business travel 1-3 day before the trip. I am completely price insensitive (I do not care if my employer pays $100 or $400 for the ticket), my schedule is hard to predict ahead of time (if there are no important meetings on Monday, I will fly on Monday. If something important pops up I may fly on Sunday or on Tuesday). Downside is smaller seat selection (I mitigate by always checking if aisle seat available before booking) and sometimes convenient flights sell out.