To use Dwarf Therapist or nay?
Personally, I don't but I understand people who do use it. From what I can tell the gap with labour assignments that occured with the pre-50 versions has been narrowed by the UI improvement of v50.xx, which was the main thing people used therapist for.
(I'm assuming this is about Splintermind's fork of Dwarf Therapist. The original Dwarf Therapist was last updated in 2012)
Got sidetracked there. So advantages to Dwarf Therapist:
Skill use: the spreadsheet format allows to see which dwarves are mos qualified for which jobs. It does this by turning them into numbers making it quick and easy to do. Plus you can centrally con trol labor assignments without having to flip between tabs
Mood regulation: You also get a spreasheet for which needs are goihng unmet. If you want your fortress to be super happy then this is useful for finding where you can get the greatest gains.
Gaydar: It gives you a quick dwarven gaydar
There's a few other things as well. I've never usied it myself. To be fair I'm an on-off user of DFhack so maybe not the best person to go for advice on utilities.