45 minutes to an hour. I try to dig up all the fossils, check my hybrid breeding, talk to each villager at least twice, complete the tasks they give me, check all my stores, and then catch some fish and bugs to sell.
I usually strive to at least talk to some villagers, buy a few things, water any flowers and check for hybrids, dig for a few fossils, and find the money and ore rocks, which can usually take me 15-25 minutes (which fits perfectly in my schedule, as I always have about a spare half hour in the morning to do whatever). However, it takes me an hour per day for me to be completely satisfied and make some progress, while 20 minutes is just enough to maintain my town and get some bells.
i sometimes go to the island ( so it's not a daily task, more of a weekly task )
and even though i let people in my town daily, i don't feel the need to do it, but just invite some people
Other than redecorating, I've done just about all I've needed to do. Just remapping the place now--which if I let it--takes hours since I obsess with stuff lol
When I first started the game, I think I averaged about 2 hours. Since then, I've been able to cut several tasks, bringing my average time spent on daily tasks to about 30-45 mins per character. Once I get my alt to a good place, I probably won't play him everyday, giving my mayor more time for extra stuff again.