I will have to get in to this habit as well.
I loosen my winch strap when I park the boat for winter.
However, it's always a good idea to do a walk-around before towing a boat anywhere. Check that all of the connections are tight, it is strapped to the trailer, the lights all work, the tires are in good shape and full of air, etc.
I once put my boat in a lake in northern Wisconsin at my sister-in-law's brother's house. I parked my truck and trailer on the seldom used road next to the launch. When I returned to pull my boat out, I found that someone had taken two of the roller wheel assemblies from the trailer (bolts were laying on the ground). I had to rig up a life jacket on the roller beam so that it wouldn't scratch the bottom of my boat!
Point is that you never know when something will break, slack, or be taken from your trailer so you should check every time.