That's weird, I usually get several hours. On the other hand, I only do editing in FCPX, the rest of the heavy lifting is done in Resolve, which actually destroys my 2013 MBP 13" (maybe I should look into proxy/cache managment, there are way more configuration possibilities in Resolve).
I'm slowly getting desperate. The user reports are as contradicting as they could be. When I look at the raw data, the 15" MBP should be by far superior to it's competition when it comes to processing power/watt. But then, some people report 2-3 hours battery lifetime, others more than 10. Some people claim software updates resolved their issues, some say nothing improved at all.
All I want is to use the 2016 15" MBP in the same way as I did with my old rMBP, just with the added power benefit. I'd gladly pay the money right now, but as long as there's no consensus on the battery life, I'm hesitant to throw my money in. For now, I can live with the struggle through Resolve. But as soon as the new GH5 hits the market, I'll have to jump over to a machine capable of 4K editing.