I'm not sure I completely understand your question, but…
In the water, yeah, I've started with the throttle in the minimum/lowest position and whomped on it, putting it all the way to the max quickly (like floorboarding it in a car). I wouldn't do that until the engine is properly warmed. I don't do it when I'm towing a tube because it seems I get some cavitation for a bit if I go too far with the throttle until the boat gets on plane.
I've also run it at WOT on smooth water long enough to see what the boat's apparent top speed is. No problems with that as long as there's no annoying bouncing (porpoising).
On the trailer, I rev the engine a few times to clear the exhaust of water. I don't think I get it all the way to WOT, though. I don't run it this way for even 10 seconds.