I sit in the GRFZ (we moved from the north at the start of last season as my kids wanted to start going) but they don't always go to every game, such as night games or when they have something on. Imagine a lot of others will be the same. We've upgraded their tickets to adults a few times if needed. Imagine a lot will be similar.
There are quite a lot of regular empty seats though, and can see when groups of lads are out on the lash they don't take their kids.
One thing I have noticed since sitting in there though is the amount of drug use, both inside and outside the stadium, especially at half time.