I think you are doing great. I think your sanding is fine, in my opinion, and just my opinion and likes, is some people doing intarsia over sand. I have seen some pieces that to my eyes, look like the animal had been on steroids for many years.
I'd like to do it but never seem to get to it, same with inlay. Maybe as I get older I am more comfortable working just in my comfort zone.. Or, maybe getting lazy. I do know I'd have a hard time spending the money on exotic woods and more sanding gear.