As much as necessary to make the story move forward. If something specific that happened in bed is necessary to further the story, show it. I'd much rather see nudity than someone's brains getting blown out. Nudity and sex can be added in a way that makes movies or TV series worth less without it - they can actually add value to the movie/series.

There's porn out there just jumps right into the fucking and there's porn that tries to build a story yet the acting is downright awful. A good thing in the middle could be amazing, but most of the time, the needle isn't threaded or threaded badly.