it is a flight manual requirement for all three trims to be run through FULL deflection checking for free movement and lack of binding etc.
Interesting the same checks are not required in airline types. You don't see a 737 crew running the stabiliser trim right through the full range of movement as part of the preflight. And that is a huge range of movement. Nor the rudder trim which takes 29 seconds from neutral to one side and same to the other side. Nor the full available range on the aileron trim either. Of course it might be required for a C or A test flight but not on line flights .