Most of the games I played back in the day had some way of resuming your progress at a later date, whether that was an actual save system, a password system, or even a hidden warp zone. What were you supposed to do for longer games that had no way at all of resuming your progress after switching the console off? Get good enough at the start of it that you could play the game faster and eventually complete it in one go, or just leave the console on overnight and continue the next day?
(and yes, my Mega Drive is currently sitting powered on because I couldn’t think of a better way to keep my progress)
The console games I played were nearly all meant to be completed in one go.
Anything without a password or save option worked that way.
We’d also rent our games, so even if there was a save file you had to remember what to do because your save would be deleted. My brother had a copy of Final Fantasy I with a dead battery and we just left the console on for a few days straight. Same thing with his copy of Zelda, but that one was somewhat manageable in an afternoon.
RNG was less common, most games were memorization exercises: Mario, Shinobi, etc. So after dying and retrying enough you’d figure it out.