10 would be better for most artists, but remember.. it started out as superproducer and songwriter thing.. that group usually has more "hits" than your standard recording artist since a lot of their work is recorded by other artists.

Also, I would recommend specific rounds, something like but not limited to this..

Round 1: Debut or Breakthrough Hit
Round 2: Slow Jam
Round 3: Midtempo Jam
Round 4: Uptempo/Dancefloor Hit
Round 5: Collaboration
Round 6: Song from an OST
Round 7: Hit Anthem/Torch Song
Round 8: Live Recording
Round 9: Cover Song
Round 10: Undeniable Classic Banger

something sort of like that so the song matchups are more comparable, or is that doing too much?