One good reason to separate is that recompiles still happen in released code (change platform/bitness/version etc.) and if you don't separate, LV will show your VIs as modified unless the installer resaved them after install (which VIPM is supposed to do if it's configured to, but didn't always work). There are also cases where VIs occasionally decide they need to recompile for no apparent reason (VIs which have ActiveX calls are particularly bad at this - they decide they have a different component from the one they had before).