I 'think' the maximum were 90 minutes ? (A C90), or were there C120's i cant remember.
Most tapes didnt have much on them as they just needed enough for the game.
Bear in mind back in the 80's the Commodore 64 had 64k, the ZX Spectrum had 48k, later on you had special 128k games which were much better.
Back then when you only had 48,000 bytes to code with programmers had to do a lot of very clever things to get the game within 48k. Nowadays 'some' devs dont seem to care how big the file is as it doesnt matter so much, but back then it was quite an achievement to get your game working fine in 48k.
God i feel old