Is it mandatory in the NBA to have a specific staring 5?
I mean i always see posts about who will be the fifth starter for the Bucks for example.
Can they just have 4 main starters and rotate the 5th one based on the opponent or the form of each player?
Not mandatory. Starting lineups change all the time, for a variety of reasons from level of play to injury. However, coaches and players seem to prefer consistency when they can. By most accounts, it is easier to play well with consistent minutes and consistent lineups. Definitely doesn’t always happen, but usually if it’s working, coaches will stick with it.