I can not account for others but my boat gas usage is down mostly because of the weather earlier this season. I opted not to venture up to the lake during motorcycle weekends (and the week in-between) and the NASCAR weekend. I just didn't want to fight the traffic or crowds this year. Some of the few nice weather days in June and early July I had other commitments but the unusual weather was a big factor for me.
The few nice weekends we've been at the lake there were just too many boats and too much wake chop for my First Mate (wife) to be comfortable. She wants no part of a bumpy crowded lake cruise so we used the boat at the slip enjoying the amenities of the Yacht Club and beach. Just another reason I've used less gas than usual so far this season. We have enjoyed a few fine mid-week days but not as often as past seasons and no where near past boat gas consumption for this time of year.
I expect to use much more gas this month (August)

. Hope the weather is nice and I look forward to seeing you all on the Lake. I monitor Marine Ch 16.