My phone (Nexus 6P) battery life has not recovered from the recent debacle where the Fitbit android app was sucking up both battery and data. I'm running version 2.75 and I even uninstalled and reinstalled (though a previous version) and it's still using the battery over 2x as fast as it did before.
I turned off all day sync and always connected and it might have helped a little, tiny bit. But now the "keep alive widget" keeps telling me to restart my phone to re-enable notifications, presumably after I'm out of bluetooth range, which I am a lot.