Some points to consider:
1- you don't have to fill the whole grip, just where you grab the grip. I'm a one hander so I barely need more than half of the grip.
2- it has nothing to do with the brand of the grip. It's more about which grip you're using. The same brand usually has more than one kind of grip.
3- it has also to do with the size of your grip.
4- it has do to with your "overgrip-applying technique".
I use only the tournagrip because I sweat too much, and it never fills the whole grip. I use a 4 3/8.