Recently unshelved some old projects & hit build.
Because of the timestamp changes every file in the workspace got marked as out of synch with CVS & there ensued much churning of bits as each file was set aside & re-pulled from the repo. Took much longer than a fresh checkout.
It would be nice if there were a "Wipe out workspace first?" option during shelving.
Given the nature of what you're doing, you likely don't need to archive it anyway