Master's farming

I'm confused after reading multiple sources with conflicting information.

I just want to get Tora to level 3 so I can get gems. I've random come across her during my leveling and completed the Corrupted Beast Den a few times. I need to do the quest a few more times to get to level 3.

Is this a daily quest or can it be done multiple times a day?

You encounter masters in the wild (they spawn randomly) and you can do their daily mission if they're in your hideout (you need them to be level 2 to be able to invite them to your hideout).

What concerns me is you say you want Tora for gems...why? You can buy most gems related to your class from vendors after completing quests that give gems as rewards (Nessa in Act 1, Yeena in Act 2, etc.) or just buy the gem you need from another player via poe.trade or pathofexile.com/trade.