Annoying, tedious and most of the time tiring. Is it worth it?
Yes, it is.
The personal enjoyment of finishing the baselines of a completely new and original character is exceptional. To bring a character to life through wording is infinitely delightful to the point where it makes you want to make more characters. Exploring the possibilities available to your fictional counterpart(s) is like living a whole new, possibly better, or possibly worse, life. It sometimes makes me think of the infinite capability of fictional improvisation.