It depends on the situation as well. For instance, last year I was travelling with my parents SFO-LHR on UA. They were in F, I was in C, but because they rarely travel and are getting a bit on the old side. I spoke to one of the F flight attendants before the flight, and had no problem going to up to visit 2 or 3 times during the trip. Each time was only 5 minutes or so, and just to check on them. Still, having flown F myself in the past, I tried to be discreet and quiet as I didn't want to bother anyone.