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)
I can’t think of any games that were particularly long that didn’t have save systems (like Zelda and PC games) or password systems. Plenty of fuckin’ hard ones that only had like 6 levels tho. And those you really are meant to bang your head against until you beat them because they hadn’t quite left the design of arcade games behind so they were still making them like you were putting a quarter in every time you got a game over.