Bob 

Thanks from me for a very clear exposition of the question you wanted answering - it happens increasingly rarely now, particularly if you frequent Facebook groups.

For me, the best analogy is to compare FT4/8 to a fishing competition. If you want to catch the most fish, do you fish in the small pond with a few tiddlers in it, or the Great Lake teeming with fish?

once the ‘catch rate’ of FT4 starts to approach that of FT8 you will see a pick up in activity. At the moment I try to make a game of it by having a QSO with everyone I can see on FT4. I would never try that on FT8 unless it was one of the quieter band.