OK this may have been the thread I had in mind when I said we had discussed this before. WW linked it on another thread for us.
ACV rinse after protein/DTs or before?
Now of course unless you become OC'd I see no reason why this principle can't be applied to co-washing as well. Especially if you're washing every couple days. I have not OC'd yet. It seems to me because you're absorbing a good amt. of condish prior to rinsing you don't need very much for a rinse out. With co-washing on very wet hair and then following with a rinse out, it's harder to gauge how much condish you actually need to get your hair effectively cleaned and hydrated. This theory works for me