It's "easier" to do it with hatchlings because they take up less space than adults to begin with... but it's actually even more important to feed young snakes separately. Young snakes are generally much more hungry than they are smart, and much more likely to make mistakes like latching onto the same mouse at the same time.

Frankly, I kind of think they're equally "difficult" for me as a caretaker--separating at feeding time is as much work as cleaning up multiple tubs. But I do house some of my animals together, and in my experience what stresses ball pythons out is any change in living situation. ie. a snake that has been living alone in a tub for years does not deal well with being moved into a big, spacious party tank--but conversely the party animals also behave in an almost depressed fashion when I move them into isolated tubs. Stress is difficult to gauge, of course, except in terms of eating habits and maybe night-time activity... but that's what I've seen.

One thing in favor of younger snakes: they do adapt to changes in housing situation much faster than older snakes, just like they typically adapt more easily to a change in feeders. An older adult may be stressed for months.