enabling unused attributes

Can one have a multipass rendering system that enabled pos, normals, multiple uvs, colours, and generic vertex program attribs 6/7, all pointing to valid data even if not all of it is used in each pass?

Or for each pass do I need to disable data not used such as texture coordinates for higher texture units if I don’t actually use that data?

I’m getting strange data in some cases with vertex attributes 6 and 7 (it uses the same data for each vertex, but 99.9% of the time it works as it should)