Is it still worthwhile to hold off on completing dungeons to ensure the maximum level epic (i.e. clear Cutthroat Grotto at level 110), or is it better to clear them as soon as you are feasibly able to do so?

I know a lot opens up once you full-clear the 9th dungeon, so my current plan was to wait until I could conceivably full-clear the 8th dungeon, or maybe even the 7th, and then clear any dungeons I was holding off on in order to complete the 9th as soon as feasible.

Presently I'm level 101 and holding off on clearing Cutthroat and Emerald dungeons, but I'm starting to think that might be a mistake.

And as an unrelated question, has anyone confirmed if the mine needs to be higher level to get the grail or not? If not, I'm heavily considering keeping my mine at 2 until it looks like I'm close to clearing the 9th dungeon. With my laborer's quarters at level 11, it's something like ~3.25 days in order to hit level 10 mines and all. Unfortunately, I'm still ~30 stickers short of meeting the 1000 stickers requirement.