I normally read the manuals for stuff I buy, but have to admit that when I bought the boat I didn't read all the manuals for the various components that were on it. Include the brakes in that category.
The manual for the truck advised using tow mode to reduce wear on the truck brakes while going down grades. I would do that on long grades if I didn't already have it on. It didn't occur to me that wouldn't be good for the trailer brakes. After reading the DB35 manual for my hub project it specifically says NOT to use tow mode going down grades with surge brakes, that it is better to pump the brakes.
I guess it is never too late to learn.