I've started.

Time quests to earn league points. I started playing to counter them. It's surprisingly fun. It doesn't progress smoothly after a certain point though... Initially, you can just steadily complete missions. If you watch videos, you can get double the rewards like coins and diamonds, but I'm deliberately not doing that. ...So, I can focus on the game without the stress of watching ads, which I think is good, so I'm playing like this.