I’m saying you want to get all the top cut in if you can. I like to see a .100 wide top cut IF it will fit. Sometimes you can’t get it all so you end up at .060-.070 wide.
I’ve seen really good head guys just get the seat on the head and then quit because they didn’t want to “sink” the valve. Getting a top cut isn’t sinking the valve, it’s finishing the valve job. Now, if you get all the top cut in you can and you keep dropping the seat you are going to lose flow.