Perspective from someone playing in an suburban area with low activity:

It can be nice because gyms sometimes don't change for days, but it's also frustrating to only get 30 for holding a gym and missing out on the daily max just because i didn't happen to coincidentally walk by a 1 star raid.

I think the idea is good but they need to tweak the amount of earned coins. Either make them stack 50 (gyms) + 20 (tasks) or if that would mean Niantic goes bankrupt at least make it simply 50 a day that you can either fully earn by returning gym mons or split between tasks and gyms.

I also would advocate for removing the "win a raid" task or at least turning it into "fight in a raid". Having to burn a paid pass just to get 20 coins isn't worth it so i don't think they can monetize it and for the player it can just be very inconvenient. 20 coins is basically nothing when even a simple storage upgrade costs 200 so limiting it to simple tasks you can quickly do at home seems fair to me.