I think that I practice in the same way that runners prepare for marathons. Gradually build up the endurance. When I know I'm going to be playing a LOT of oboe, I tend to practice in longer spans, in order to get my full embouchure strength (I mostly play English horn with the symphony, and non-oboe stuff at other gigs). I do this same kind of thing preparing for oboe recitals. The longer my practice sessions, the better prepared I am for longer playing. This also means less down-time in practice. Working on Pasculli solo works is a great way to achieve this, or longer etudes (Silverstrini).