I always feel sorry for the production team whenever I hear the TNG cast talking about their antics on set. There's nothing more frustrating than working with talent who turn into annoying children when it's time to do a shoot and time is of the essence. I've never heard from any of the TNG production technicians, so I suppose they could have been in on the fun too. But I seem to recall Marina Sirtis and others commenting on how the production crew hated the cast (when cast members were out of control) because it took way too long to get a decent take and all they wanted to do was get the work done and go home at that point.
As far as actors complaining about not getting enough screen time, you can tell who the awesome actors are because the best actors end up getting the most out of the writers. What an actor does with what they get and how they interpret the role is a key part of whether/how the character develops. Even with very little or no dialogue, great actors are always fun to watch on screen. They seem to pull emotions and chemistry out of thin air. While weaker actors just take the bland writing and spit it out in an equally bland manner. There plenty of examples of both in Trek. An example of a great Trek actor is Andrew Robinson (Garak in DS9). He could say the most mundane line and still be incredible to watch, even through the makeup.
But, yes, it seems the cast of TNG are BFFs.