I don’t know what records you are referring to, but my guess is you’re right, it’s subtle because any more than that would be distracting to the song. Some records are meant to be dry and some wet. What does the song call for?
A record like Grandaddy “Sumday” has little or no reverb or delay from my end. I’m using a lot of different sounding compressors to give the record depth and to bring out the natural room reverbs of the instruments. Some records, like the one I’m mixing right now for a band called “The Open”, have all my analog delays firing along with spring reverbs, plate reverbs, room reverbs, it’s got it all. It’s fun time.
Sometimes the point of using these delays or reverbs is to help add depth in a very subtle way. There might be reverbs and delays going on, but they are to be felt, not heard. I assume that is the case on the kind of records you like that I’ve mixed.