Can also depend what else is plugged in, to which ports, Windows settings etc. UPC's generally only have a couple of battery ports, the rest are just protected ports, but if the monitor is also on a battery port, and not set to sleep or the windows timers are set with stuff like 'wake on Lan' etc, you'd be using a lot more juice during 'sleep' than just low power C6 state, and possibly hitting C0 (On) state instead.
Waking a pc from sleep isn't a gradual buildup, like waking up on a lazy sleep-in Sunday morning, it's closer to Christmas morning at 5am with a 5yr old suddenly bouncing on the bed, and the resultant adrenaline rush. A PC waking up on a UPC several times, not going to last that long.