Until me and sman met and got married,, I always used separate gauges (22 every day, 22 4way evac, 410 every day, 410 4-way evac) since the honeymoon stage me and ms. Sman share the love with everyone.
Same gauges all the time. I try to do the pull the through technique when removing them(sucking everything through low side) and then I leave the ball valves open so nothing is left in it. I purge the hoses with system pressure every time I hook(I dont work on critically charged systems)
I've already seen dry r-22 units and replacement compressors using POE so trying to keep gauges dedicated to one type of oil would be hard.