It seems to me that 20 milliseconds ballpark time gap is hard to achieve outside of a dedicated RFZ-type room. Imo there is still arguably worthwhile benefit from a 10 milliseconds ballpark gap, which is the target Geddes shoots for (he cites Griesinger as his source).
Imo the ideal role of the in-room reflections is to be
carriers of the venue cues on the recording, but
without drawing attention to their own inherent "small room signature" cues. I don't think this ends up being radically
different in practice from what you have described in your posts in this thread, though it's arguably looking at room reflections through another lens.