I'll add my experience with dry yeast, which I use almost exclusively. There are people who will advise that you should always rehydrate it. I won't say there's anything wrong with doing this, but I will say, based on my experience, it's not necessary. I have never had a problem with simply sprinkling dry yeast on top of the wort.
I want my processes as simple as possible - simple processes are inherently less likely to have process variations (fewer steps = fewer chances to deviate). I'm a kitchen brewer but I've made hundreds of batches (including a prize winner in the one contest I entered) and have been at it for well over a decade, so it's not as if I just got lucky.