How long, is to long in the Gym/workingout?

[zerkling]

hi so I been starting a new work out routine and I'm just starting, I'm trying to make my times lower with still maintaining good form/rest time etc. but was curious if a 1 hour 30 mins is to long, I finished with 1 hour 27 mins but I'm just afraid that lactic acid is going to eat at my muscles lol any help would be good thanks