Early days, batteries did not last long, before 2000 I was working replacing access system on BT buildings, and for the first time had to use battery drills, the batteries would take a couple of hours to charge, so the whole job hinged around the batteries, start drilling a hole for a cable in a wall, and when drill went flat, move to other work until recharged. I used my own battery drill as a screwdriver, we were on bonus, so waiting for a drill to charge cost us money.
Today batteries take around 100 minutes to charge, with a good charger, so if the battery will last 100 minutes, the two batteries means continuous work. I have four batteries for the garden tool, which uses two at a time, and a rapid charger which will charge two at a time, so no problem with drills which only use one battery.
However even in the days of the B&D mains drill, it would get rather hot, mainly the gearbox, so still had to give the drill a rest. I remember the first hammer drill, it worked so wall compared with non hammer, thought it was so fast, and then we got SDS, and the hammer drill with chuck seemed slow.
My only complaint with new battery drill is no rotary stop in SDS mode, so can't use chisels, but I should not use tools which vibrate anyway, so not really a problem.