Exactly what I do with my ancient series 3, I have had no issues unless I forget my charger. I can go maybe 36 hours before a charge, closer to 30 if I do a few workouts.
That all being said, my fiancée and a friend both have series 3s that can’t even stay alive for 12 hours. I had my watch for a year longer than they did, so it’s not an age thing, I just think the batteries are very hit or miss.