Perhaps you were lucky!But that was not the question, was it?
I thought it was a discussion. Having been through a number of installations I find interesting.
Assuming a system is piped correctly, I would say no, I (generally) do not see any value in having multiple drains.
One shop I worked the mains were slopped away from the compressor. Every drop came off the top of the main and elbowed back down. Every drop had a drip leg with a drain. In the morning we would turn on the compressor and walk the shop and drain the drip legs and there was some moisture in all of them. It may have been a few drips, or to the end of the line had a 90 elbow pointing down and it had a bunch of water in it every day.
We also had a huge cooler made of black pipe that wound it's way up the wall. This was on two 10 HP compressors.
My own shop had the main draining away from the compressor and a drain at the end. There was always a bunch of water at the end. Every day of two I would open the end of the main and let it blow and it would alawys blow out a bunch of moisture.
IMO, I would rather have the water drain in the direction of air flow.







