I've had 8 hours + with a trick I found.
I found when I left the charger on all night and took it off in the morning, the battery seems worse that morning and not accurate... If I take it off the charger for the night at 99%... In the morning it's still at 99%. I'll plug it in in the morning until it sits at 100% for about 5-10 minutes and take it off. Every time I've done that my battery has been 8 hours + and have gotten at least an hour on 100% alone.
This sounds crazy, but I tried your trick and I got 4.5 hour usage and 21 hour standby (10 hour was on airplane mode) with 57% remaining with 3G. I don't stay at 100% for an hour of usage
Usually I only get 7-7.5 hour usage max. Likely your trick works