It must vary depending on the mood/apethy of the airport staff and thier targets.
Although It's been a few months since I last used them, every time I've flown from EDI with Ryanair for the past year or so they have had a small cardboard device which has the exact dimensions of the allowed cabin baggage and they have gone right down the line checking every single bag that looks like it won't fit in. On a flight to Stockholm in March they caught out at least 3 people at the gate with this!
Same can be said for my return journey from Stockholm Skavsta where they also weighed cabin baggage in addition to the measurement device. Again, several people were caught out, by having a bag that was well within the allowed size...but too heavy!
I also returned from Billund to EDI with Ryanair in late May and they were again checking the dimensions of the cabin baggage. Never had this when flying from PIK, DUB, STN or any mainland European airports!