If you are losing 10% per hour and you are not using the phone during that time you have an app that is either very active or is stuck in a loop and misbehaving. If you are using the phone and losing 10% per hour on LTE it may be due to a weak cellular signal. Note that all of the specs say "up to..." That's a best case with a good signal (5 dots). The phone will use 10 times as much energy if you have only 1 dot because it must increase its output power to maintain a connection.
At 10%/hr you should get 10 hours of browsing, which is not that much lower than the 12 hour spec. Note also that the battery gauge is not that accurate; that 10% may be 8% or 12% if you only measure it for 1 hour. The best test is how much time you get from 100% to 0%.