Hello! Thanks for the feedback and for playing our game!
You can press A to skip watching the dice roll animations if they are too slow.
The scenario where you'd want to roll lots of dice is if you are running low on time (the clock on the left side of the dungeon crawling UI) or if you are feeling confident and have plenty of dice to use. If you rolled low amounts of dice the whole time then you might run out of the 30 turns on your timer. Rolling small amounts of dice allows you to be more careful and strategic with movement/how many steps you'd like to use to rest with. If you roll many dice every time, you'll save turns on the timer by getting to explore much more of the dungeon however you'll have multiple encounters (more loot) that will damage you a lot making it important to heal. If you used all of your dice, then resting will make you lose. So it's a bit more risky this way.
TL;DR Using fewer dice to roll can be safer at times and rolling many can be more risky depending on circumstances. Try to adapt your rolling to what situations you find yourself in.