I didn't enable sabatoge until I was in France for a while and with my careers in the Med, I've had it enabled since I started there. I try to give the boat a good shaking out on the first day out to make sure everything is working. I have been caught by suprise a few times though and even had to return to port a couple of days out.
Can't speak for a IIA, but in a VIIC, I had enough air for 3 blows, but I was flooded pretty bad and around 225m on the last one but it got me to the surface.....briefly.