10:57 PM, Wednesday January 11th 2023
Hey, no problem!
1) You can try it and see if it helps you, if it doesn't help you then you don't have to do it.
2) The way you practice right now is very good and I wouldn't change it. Instead, after you have done the 20 - 30 torsos from imagination, I would do the rotation exercise from imagination as a test to see if you still struggle with certain angles, and if you do, you can study those specific angles. Alternatively you could use reference and do the rotation exercise while you are learning to better understand the subject. So depending on what you want to do you can use this exercise in different ways. All it comes down to is how you want to use it.
After that I would incorporate what I've learned into an actual drawing and see if I've improved or not, 9 times out of 10 there will be improvement because I've drawn about 200 torsos all from different angles. If there wasn't any improvement it could be because I didn't make the learning hard enough (I.e stayed in my comfort zone and didn't try to learn).
The critical aspect of this is applying what you've learned to actual drawings because there's no point learning random stuff if you will never use it in a drawing. There's a good analogy for this. Say you had a math test that you have to study for, you wouldn't start studying a bit of english, a bit of science etc. You would first do a practice test for math to see what you know and then study the bits you got wrong. For drawing that would mean actually making a piece of art and then studying the bits that look bad / you don't understand very well. However, when you do make a piece of art you should do it with your full effort and try to make it the best you possibly can like you would in a math test. If you don't then you can always say "I didn't do my best" and then the mistakes / things that bother you will never be addressed and fixed. Even if the piece turns out "bad" after you do your best you shouldn't get discouraged because at the end of the day all we can really do is our best.
Anyway, hope this helps!