3 angle valve job vs 5 angle valve job

I've been reading more about people using 5 angle valve job on their cylinder heads. Is there a advantage to this on a mild build? With going to a 3 or a 5 angle valve job should the seat's / valve's be replaced? On the 5 angle valve job what are the preferred angles?
On a mild build, probably not, but, it would depend on what it would cost you to do it. If it's cheap (your definition on that), why not? When I was grinding my own stuff, I used 15, 30, 45, and 75 degree cuts. Just those 4. The 15 and 75 were mainly just to clean up rough or protruding edges and throat the bowl area a bit. If I wasn't doing any porting, I also buzzed any rough casting flaws especially on the exhaust side.