It's late, and I need a break, so...

Can data be 'over' normalized? As I'm sitting here trying to decipher the 20 to 30 nearly perfectly normalized related tables in this program, I'm seriously starting to question how much is too much. The data manipulation at our disposal with well normalized tables is phenomenal, but at what cost? Is there a limit to the complexity of relations the mind can accurately maintain? Are there any rules of thumb as to what that is? This then begs the question of how best to denormalize certain data.

I was just looking at the VFP SCX structure for kicks (yep, that's what they call fun out here in the boonies). It seems awfully de-normalized to me. I would think each class library should consist of several tables, not just one. Shouldn't they consist of a class table, and perhaps a properties table, a methods table, etc.? Why does the company that develops this database system not take advantage of this normalization capability?