I think I wore 15 once, with three leotards. Was a mixture of sheer/control top/opaques. Took a while to get hem all on, as I had to keep stopping to rub my cock

These days, when the missus and I want to play, we typically each put on two pairs of control top, the first pair with the gusset cut out. That way I get to rub her pussy through the nylon for a while, then when we get down to business we can take off the outer pairs and fuck through our pantyhose without having to keep tearing holes in them. Plus the feeling of my cock between two layers of nylon is REALLY nice! Sometimes if the mood strikes me I'll pull on a third pair, but haven't gotten much higher than that in a while.