For what its worth, I believe it essential that some level of standard be applied; perhaps based on a 'demonstration of competency in prescribed actions' basis.
I am aware of one PPL who had not flown for 20 years being signed out after a single 1 1/2 hour flight with an instructor in 1999.
He had no idea of contemporary radio and airway procedures and had only dropped in to the school with the vague thought of taking it up again. (He had just passed his medical with the same thought in mind.)
He was not aware he was doing a review until after the event and even then had to have the rule explained to him.
While he walked away from his landings and they could (just) use the aircraft again, the thought of being legally allowed to carry passengers scared him sh*tless and he dropped out again. He was not competent and he knew it.
His comments on his perception of the drop in safety standards from the time he learnt to fly are unprintable - even on JB.