1) Depends
2) Depends
Honestly bsem, its going to boil down a lot of factors:
(a) Form
(b) Consistency
(c) Lifestyle/Health
(d) Genetic disposition
Virtually every PE exercise (barring the very bizarre ones - like using bee stings) has produced gains for some men. Some men have stuck with a lot of different exercises and get nothing. Some of that set may try something different and all of a sudden - gains. PE is not an exact science but there is a lot of information.
I think the most important factor of my list above is consistency. If one isn’t consistent, then how can progress be made?
Have you started the newbie routine?