I'd like to relate a personal anecdote. I foolishly allowed my DL to expire a few years ago and procrastinated on the renewal. By time I did try to renew, it was too late and I had to retest. It was an eye-opener. I had indeed forgotten many things since I was 16 (decades ago), and others I never learned. I'm a better driver today for having had to retest. I now see how poorly others drive and I'm much more defensive and less aggressive that I used to be.