I try to go to a ski school for a week each spring. Usually I'm in skiing shape by then, able to ski 8-10 passes per set. Probably should say I'm 52 yo.
I will alternate 1 set and 2 set days for the week, and maybe double up with 2 set days at the end of the week. That's about as much skiing as I can do for an extended period.
Four sets in one day is nuts, let alone multiple days in a row.
DEFINITELY go and get coaching. You'll be glad you did.