My biggest experience with SB comes at the U21 level so I'll use that for my example. I find that SB being within a couple(say 14 ID 12 SB) make the defense better. SB has also been talked about in other forum posts(I don't have them handy so my apologies) on being necessary to run zones.
I once had a team with 1757 players and was $25,835,360 in debt. This is not that team. Join the Discord group open to anyone, but especially for USA managers to improve your club or get involved with the U21 and NT programs
(https://discord.gg/cKpNkt2).