After I buy the watch, I used it for 2 weeks 24h and I never had any problems, even after the 4.70 update.
Then I start using the watch just at the weekends, with my workouts. During the week I disable the HR monitor and this weekend it fail me in one workout.
I think you just answered your own question!
Max
More you should not need to.
The only reason you might is if you are trying to run some absolute max battery test.