would you play with all 3 or 4? or would you just pick out the tiles you want to play with?
i can imagine having 2 sets of say gold mines but i am not sure if 3 sets would be usefull
It's all about balance. Difficult to say what to recommend on its own. Depending on what type of game and expansions you play sets the appropriate amount of tiles to be used.
Some things to consider:
Diminishing return. More tiles quite often means a longer boring game at the end, especially with expansions that score too few points such as Traders, Gold Mines etc.
Investing a meeple or more only to get an average score for each between 4-8 points that takes several moves is not worth it. Not always at least.
Cloisters. Every expansion except Corn Circles have these and they can quickly start stacking up to a ridiculous amount. My last game had almost, if not more, than 1000 of them!
You can try remove some of these and, for example, replace a cloister gold mine tile with another gold mine tile without one.
Paul