what is the best way for a compressor
leave it under pressure or leave it empty
keeping it under pressure might make for more condensate as there is more air which means more water and also more pressure on the seals
but the seals could be designed by a clever engineer and do better when used as designed
leave it empty and with drain plug open might let condensate build up inside as it might be a little cooler but then the seals are exposed to air and might dry out and shrink
or forget about it and just make some stuff which is what i usually do with this sort of dilemma