If you mean opening drains and allowing to run for a couple minutes or more; absolutely, every time it is used. A lot of very expensive scuba compressors need full rebuilds every year long before they should due to idiots not shutting them down like that. For a commercial place that uses them 7 days a week, much less of a problem, but still bad. For a hobby diver that might shut it off late season improperly, and not run it again till next summer, can be in need of full rebuild with 10 hours on it. Water trapped inside all winter/spring can corrode the living hell out of internals. Water by itself is corrosive, with hydrocarbons and other stuff in the air we breathe that water trapped inside a compressor is somewhat acidic making it real bad. The point of running with drains all open is to cool down the interior of the compressor, so water doesn't condense when it is shut off and cools to ambient. The man I bought my compressor from made a very good living for decades rebuilding low hour bauer's he bought for pennies on the dollar from idiots that ruined them and then selling them. He told all his customers exactly why they always need to shut down like that. His personal bauer, he was a master diver, was 30+ years old with thousands of hours and never opened, he took care of it.