The only time I trace is if it's for a task in the background that is especially precise--so if I get a 3d render of a building and I need that framework, or if I have a photo of trees and I do parts of the tree and then take those parts and mix em up--photobashing essentially. But I do that with a lot of knowledge of 3d and backgrounds from years and years of study. I'm only doing it to save time.
But like others have said, the thing about photos is that tracing tends to look incorrect. The lens we use in cameras will distort the human figure--especially faces, so when you trace you are not actually getting perfect anatomy unless the shot was taken from very far away. We don't notice this in photography because we are taught to never doubt a photo--but in illustration it will stick out like a sore thumb, so, learn your anatomy. Still use reference photos, but check it with anatomy.
(this is also true of using 3d renders, PS--cameras will distort your mannequin, so make sure to check that anatomy)
When it comes to your own personal work you want to be careful. I saw a picture the other day someone did where the face of the full portrait was very clearly inspired by a different artist's work--they very clearly traced and then used the liquify tool to make it their own (it had a certain color pattern) and while it technically wasn't breaking copyright--OH BOY was it a bad look. The artist they were copying was very twitter famous, and did not approve of them selling the image, and asked them to take it down, and they were refusing because legally it's different enough to be allowed, and then all these other big time artists were dogpiling as well as smaller artists and OH BOY was it a situation.
So like...there's a 30% rule that you have to change enough so only 30% of the original reference remains but...be so very careful. If there's something particularly noteworthy about the original, a certain idea that has become so popular that it's that artist's brand...not even liquify will save you. You really just need to do something different.