I think it depends on the training and for how long one trains, ever played Fable Anniversary? I think its like the how the chain of hits builds up but like Goku said if they don't properly rest they won't get as strong as they could though so that affects it too.
I would think it adds to it which is why transformations are so extreme when they do multiply. Also I think it’d make sense in context when they say “I’ve gotten a little stronger” as opposed to when they say “He’s over doubled his power!!”