That's how I do it on the newer cast iron, mostly Lodge, that I use at camp. I finish it off with 80g then 120 g on my palm sander.

I been doing more snooping since I made this post. Does seem lodge is the only long time america company. that makes cast iron wear for general public market. Not a designer type label.
Seems there is about $10 spread between the best price I found for a lodge dutch oven and similar brands. All the others I looked at were Chinese made.
So anyways I decided Im just going to pay the extra $10 and buy lodge.
As for the rough finish on lodge. I have a couple of larger lodge pans I bought years ago. I didn't like the rough finish in them right form the get go. I didn't even need the internet to tell me my angle grinder with a flap disc was the answer for that. Once I own something needs fixing if there is no warranty for. I fix it the way I want.

Mac

Good choice IMO Mac.

Smithey cast iron is made in Charleston, SC. Their surfaces are highly polished. Very nice but expensive