Was wondering if any of you guys had a take on this.
Would you ever let a student, be it instrument, private or commercial, fly twice in one day?

My policy thus far is that I never schedule more than one flight a day, I just believe that they actually learn quite a bit between every flight, and during the night while sleeping. Be it muscle memory setting in, or the brain making connections while you're sleeping etc.

Of course your goal should always be to let the student finish in as few hours as he can manage safely, and as fast as he wants too (depending on how serious he is).
Most my students have limited time on visas, so they want to do training quickly, I was wondering if anyone had any experience as to if its recommended or not?