sauce: https://twitter.com/NahatALICE1/status/1364166368967368712

The time you spend playing is higher at the start and start to drop off later on as you catch up to all story quests.

If you just do daily commission and some domain to spend your resin, 30m should be more than enough. My daily play time is maybe 3-4 hours per day, but I do daily commission, farm daily crystal chunks, do elite mob runs and lastly domain to spend my resins.

You generate 1 resin per 8 minutes. Resin max cap is at 160.
So logging in once per 21 hours is sufficient.

Spending 160 resin takes about 10-30 minutes depending on how strong are you.
You get 4 daily quest to do, takes about 10 minutes for all of them.

30 minutes a day should be enough but this does not include your story progression, events, weekly/monthly quests and other less important daily quests.