It's enough to go from ~60% to ~80% and fits in as a daily habit, so my watch is almost always between 65% and 80%, It can track my sleep (I exclusively use my watch for tracking sleep, tracking exercise, tracking heartrate and telling the time. I don't have notifications enabled)

Then perhaps the best feature of charging the watch in this way, is that if you forget to charge (or unexpectedly away from home), the watch will always last for 3 extra days.

And if you are going away on short weekend trips, you don't need to pack your charger, just make sure it's at 100% before you leave for a reliable 4 days of usage.