Fatigue
Im a CFI in California, and work in an abnitio trainingprogram were we quite often push 10-14 hours a day 5-7 days a week for nine months straight.
Does the students suffer in the program?
From what ive seen, no, not to a big extent.
The ones that suffers are the instructors from a sosial aspect and the inability to expand on current knowledge because there isnt enough time to both work, sleep AND read in 24 hours.
But the passrate is very good in this school and I would without any hesitation let my students fly with my girlfriend while I were left at the ground (which is close to the highest praise I would think).
But as I said...It hinders the CFI's time to refine his skills on the theoretical level. Ive noticed lately that my own and others flightskills are very good, but the booksmarts are suffering a little.