Two U60's and a U30 let me shoot 5 hours of footage, with a bit of life left in the U30. The camera is on all day, standby and shooting. Hope that helps.
My 4+ hours includes maybe an hour of shooting. I leave the camera on constantly. Anyway there's probably only negligible difference in consumption when "rolling" as opposed to standby. I guess the tally light uses some extra power (if you have it turned on).