Just MHO, but, "for every day shelves" as you state, I would say 4 ft. is too deep. For actual long-term storage, maybe not. Depends on what you are storing. Most of my shelves (against a wall) are either 18" or 24" deep and that is fine for, "every day shelves". But even then some things get lost or hidden in the back.
If you are storing your winter tires, spare engine block, or bags of fertilizer then maybe 4' deep is OK. But even for these big things, I don't think I would want anything more than 36" max.