You should be able to build more than 7 Sylvan Shrines. They increase your storage cap quite a bit.
Try not to get too many doubles, only if you think they are really necessary. All the other trees should be Sylvan Shrines if you want a high cap.
I'm at 48850, I could get 2 more Sylvan Shrines if I wanted and my Settlement is only level 2 so not fully upgraded.
Ingame name: Quindiniar