You can. It's just better to have two separate days because you generally don't want to squat and deadlift on the same day, or bench press and overhead press on the same day.

>>75613773
because then youre spreading too much of your energy thin trying to hit every single muscle group in one session
you either dont do enough volume for each muscle group trying to preserve your energy across the session and so you get a shitty workout, or you go all out in the beginning and then you dont have the energy to do well for the rest of the muscle groups so you get a shitty workout
fullbody is a meme

>>75613773
Diminishing returns. You're better off breaking it into muscle groups and putting that much time into those groups.