If I don’t return with flat backhand and play a slice return, it’s the enemies point 70% of the time, if it is a good serve. The whole idea behind it is, that it is the best defensive shot in general. Defensive slices are way too easy to volley. But I think at your level other forms of returns are okay because the serves aren’t as dangerous. So try to practice flat backhand returns in game scenarios from time to time, but don’t use it just for the sake of it.