Quote Originally Posted by strangebloke View Post
As the number of powerful narrative-impacting tools increases, the number of potential issues the DM has to account for increases, and the difficulty of balancing encounters and apportioning loot increases. In my own experience and in the experience of other DMs I've talked to, this is a serious factor in preparing notes and a pretty common cause for not being able to get things together for a session.

It's not the only reason a session falls apart, but at least IME I still play with everyone I ran my first 5e campaign with. They're all still in the area and still playing and they all still get along with me. But we're on our third campaign together because the earlier campaigns had gotten too exhausting for me so I gave them a proper ending.
As the Player Agency increases the GMing prep requirements increase. This can lead to the GM changing prep methods to a more efficient method for that volume, or to the GM doing more prep, or the GM having more holes in their prep.

As the number of powerful narrative-impacting tools increases, the Player Agency tends to increase.

Personally I have found sandboxes are not hurt by higher levels nearly as much as more linear games (like the barely linear node based games). This is because the increased numbers of tools ends up having a smaller relative increase on each dimension of the player agency despite having a greater marginal increase. (Increasing the dimensions of a box by 1 inch each increases the volume increases the bigger box by more volume but the increase is smaller in proportion to the starting volume).