Windows estimates on how long anything takes seem to be pretty random. For battery life, that seems to be exacerbated by the manufacturer's power management software as well (and I haven't figured out which lies my new HP tells, compared to the old Dell.)
We have a new program from the IT department at $DAYJOB, which puts the machine into hibernate overnight if you haven't used it for an hour or so after 7pm. (These are laptops, so the energy the company gets to brag about saving is on my electric bill, not theirs, but I've got electric heat so it doesn't really save anything.) The big impact is that the VPN connection drops, so I have to wake up the PC, then log in to the VPN, then before I do anything else, go into the browser and reload the autoproxy, so the firewall doesn't replace half my tabs with non-restorable "your proxy settings are wrong" banners. Costs me about 15 minutes extra in the morning, though I can get some of that back by making coffee while I wait.