I drain mine occasionally after reading a comp thread. Some of the stuff in these threads that pass doer fact is a bit wonky. A bit like some engine oil thread,,, I did this and 2 years later it is all good so what I did is correct etc.
I about blew myself up when I was a kid with some of the stuff I built, more than once and its scary to think about and I go thru it with my kids when I have a chance. But I work with air all my life in a lot of places and never seen it and only a couple places on the net and the pic gets passed around like the flu. 5 ounces of water is different than 5 gallons and even that may not matter, the tank is never really dry anyway.
The failures of auto drain type things however are numerous and some of the reasoning behind it is just as faulty and no promise of great performance.
I am not sure at what point I will test my stuff, its all old. I am a fan of vertical tanks however, seems it cant be great to have condensate lay across the bottom. Having said that my 1972 has been on constant, had 1 crack on a motor mount. Its been well abused.
Also have multiple buildings, tied 3 vessels together with some left over tubing to make a common drain. I kick the valves on occasion when a thread like this comes up. The little red we got at sale for 50$. Was really a liability, had to fix every piece on it except for the motor itself. Ran for a few minutes, all was well till we put it to work, someone had glues a hole in the tank where the wheel brace was welded on. Cost me time when I needed it, would have been cheaper to buy new.