I would be surprised if every Lair Assault adventure used the same rules. An encounter where stances end, for example, should not be a shock to players, even if the norm might be that they stay active (the default rule when no short rest is granted). Powers like Moment of Glory will be expected by designers.
I also wouldn't take it for granted that team build x will win at any LA session. It could very well be that a team or PC build that does well in one adventure will do very poorly in another. The fun of constructing a PC or team is in part based, I would expect, on what is optimal being different each time (or nearly so). I imagine the program will be tweaked over time based on achieving the right challenge level to make it fun for the audience (itself a subset of all players that play D&D).