Enjoyable... I guess, but lots of plot holes.
1- if he was so good of a manga assistant and is able to do anything... he might as well make his own manga.
2- if he is bad at making a plot or storyline, he can just do what the guy who redraws One Punch Man does.
3- That author is slow because she has to use a hand for masturbating... she can just use "toys" or vibrators handsfree, a BF, etc.
4- I'm sure there are assistants that would want to stay... for reasons... instead of leaving right after seeing her masturbate.
...ignoring all that, and this would be an ok read to past the time.