There is a saying among organists (think pipes, not hammond) that the most important sound, or stop, on the organ is the room, obviously speaking of reverb. Beyond the obvious though, it speaks to a performer's awareness of how to use the room to an advantage, which implies real time association with, rather than simple application of, reverb. When laying down parts, it helps use the room as an instrumentalist would (that's where they play after all). In most circumstances that translates to getting out of the way and letting the room take over. If the reverb isn't there, there's no way of knowing what's really going to happen. Applying it after the fact is another pitfall for the same reason. A muddy wall of sound, verses the sensitivity that each performer works with to maintain clarity and light. This was really a difficult concept for me to get down, and took close to ten years, so if it doesn't immediately make sense, don't worry; it will. It ultimately happened as more of a feeling or intuition, but it started by focusing on what I wasn't hearing. In other words, if this interests you at all, have some fun and try listening to a recording, maybe a solo one to start with, and listen for what the performer ISN'T playing, especially the space between notes and phrases, and for the musical elegance of "tossing a note away" so the room can take it.