Thanks. Yes that was the intention for the hourglasses. For a too long time you could use always the same path. So I needed something to "distract" the player. I first thought of an enemy - but nothing which came through my mind would have fit to the game. Therefor I thought about going for rewards (in case of time).
Maybe a second hourglass would've been also a good idea. That could've solved the issue with "running out of time too early" and the player would've to stay longer within the "maze".