Of course you improve; all I'm saying is that by having your base training signed off and then the award of a TR that you have demonstrated the ability to operate to a set standard and, should the worst happen to the LHS then you should be able to arrive back at a benign airfield and put the aircraft on the ground. It is not like you're an apprentice electrician who has no qualifications and learns 'on the job' over a period of years before taking an exam!
Maybe my first point was poorly articulated.