This is the advice I was given when I started exploring this thing too many years ago. The problem I encountered was that one can't really spend time as a submissive without being submissive. It's almost as though there's an expectation that everyone's a switch with a preference, rather than inherently dominant or submissive.

I think there's value in intellectually knowing some of the sensations involved, but even that has limits. There's a mindset submissives have that, ultimately, makes them feel things differently. You should always have an idea of what something feels like, but that isn't what the submissive is going to feel, so you have to learn to translate the sensations.

My own "spendiing time as a submissive" consisted of a lot of screaming ("No, it doesn't feel good, it'll never feel good and if you don't hurry the fuck up and swing the damn thing so we can get this over with, I'm going to shove it up your ass until I can pull it out through your fucking nose ... ma'am") and a broken rack frame.

If someone's at all switchy, then maybe it's a good idea, but for someone who's inherently dominant there's far more value in a mentor/mentee relationship that concentrates on actual teaching.