The problem with multi day battery life is you never get in to a routine and you get caught out every time. I had a pebble watch which had a 10 day battery life and almost every 10th day it would go flat on me mid day or I'd get a warning about low battery while I'm outside and then forget about it when I get home.

Now I have an Apple Watch that lasts almost but not quite 2 days, I charge it every night and it has never gone flat on me and I find it no hassle since I take it off before bed anyway so I just drop it on the charger.