This may shock our younger viewers, ( and I’m showing my age), however when I started flying, unoptimisable and including getting my ATPL you went to your DME for a medical. If you passed, he/ she gave you a slip of paper. You could the walking in to your local DCA/CAA office, hand over said bit of paper and they would revalidate your licence on the spot!
And best of all there was no fee charged!
For those who may be operating internationally, the 4 month revalidation by the DAME may not be accepted if ramp checked overseas, as the ICAO standard only permits a 45 day extension.