At the end of the day, it’s two very different checkrides, but they’re based on the same material and aircraft maneuvers.
The benefit of keeping them close together is you’ll DO them in the Commercial and you’ll TEACH them in the CFI. Same material, completely different role and goals.
Additionally it’s been told to me that switching seats is about a 50/50 thing. And I learned from experience that is also 50/50 between aircraft. I switched seats without any problem whatsoever in the multi, and found that the 300 hours of time I had in the 182 worked against me a little bit in the single and I had to practice more in the single than switching seats in the twin.
The biggest hurdle is changing mindset from doing to teaching. Pick up a Kershner book and imagine yourself knowing that material well enough that you could write it. (No offense to Kershner, obviously a beginning CFI isn’t going to write and teach as well as he.) Practice teaching all of that material to an empty room, your dog (they love to listen) or anyone who’ll put up with it. Use a whiteboard, a paper and pen, books, aircraft models, all the stuff your CFI did.