Bluetooth Always On
When I bought my T616, I had quickly concluded that I should leave the bluetooth disabled to save the battery. I'm finding now that when leaving it on and idle, the phone lasts 3 days on a charge instead of 4. That's acceptable, so I'm not going to bother turning it off anymore.
I think my initial conclusion of it lasting only 1 day with bluetooth can be blamed on the excessive use in that first week or two.