The battery life has a lot to do with your signal coverage.
Take this as an example. For the first few months with the phone I worked in an office with poor signal reception. I mean bad. It would be hunting for even a 1X connection on minute, then showing full bars of 4G the next, just to lose it all 10 minutes later. (It was the building, not the phone). Now I'm in a new office that has excellent 3G coverage (4G seems to come and go, I blame Verizon).
My routine is the same. Unplug at 6:30am, moderate use throughout the day. At the old office I'd be down to 30% or so by lunch (12) and if I didn't charge it I'd die around 5:30pm. At the new office I actually forget to charge it during the day sometimes. It'll last until 8pm. And that's using the phone a good amount during the day.
HTC One M8
HTC Droid DNA - Retired
HTC Thunderbolt - Retired