When it was the old AFI / QFI system you had to get a stamp in your logbook for each type if you were an AFI.
Looking back in my logbook I did check flights with my FIC instructor in PA28 & PA38, (test was on C152) and then CAA FCL stamped my logbook.
Similar to the type ratings for cessna, the 152 test was valid for 150, 152, 172 & 175 and the PA28 for all engines / variants.
Once you were a QFI you didnt need to get these stamps although there may have been an experience restriction.
So - its nothing new basically.