Speaking as a Dragon veteran:
As a general rule, people still use 7/21 anyway, even at MOTD. In fact, it is encouraged to ONLY use 7/21 when you are driving, because you want to be able to interact with the other MINIs as well, regardless of what club they are from. After all - if there's a traffic obstruction or a speed trap, don't you want to know about it?
22/22 is primarily for us to use around Fontana Village, especially when 7/21 gets too busy. I often carry 2 radios around Fontana - one set to each.