My thoughts isnt constant tension on the springs or straps that might wear. Its the constant tension and pressure on the transom, eyebolts on transom.

 

There is a lot less tension on the anchors for the winch strap and the tie downs when the boat is stationary than there is when travelling over the road.  It isn't the tension as much as the shock experienced when on rough roads, crossing railroad tracks, or hitting a pothole.  There are times the force at those tie down points is two or three times greater, maybe more, than when the trailer is at rest.

Heck no!  I figure I've done good if I remember to tighten them in the first place.  Murphy's law being what it is, I'm not about to tempt fate and test my memory!