Was going to say the same... I've been in projects where the abstractions made what should be a trivial 30-60min change, with tests, blows up to almost a week just because all of the layers that need to be worked through.

To GP: schema debt is usually from adding stuff before you need it... it's almost always pre-mature and one should have a good migration strategy in place early on in order to support destructive (or at least not-simple) restructuring over time.