FWIW I typically get an adapter for each lens rather than take them on and off.
Make sense, if an adapter is inexpensive. My point is buying a good inexpensive lens (like Rokkor, for instance), $20-$50. In this case, there is no point buying an expensive adapter. I can buy $10-$15 adapter on ebay. Are they any good?
... I had great luck with rainbow imaging adapters from eBay...