Gaining mountain skills and experience doesn't have to mean picking the toughest gnarliest route and clinging on by the skin of your teeth at midnight in winter! You spend a day on a mountain. It qualifies!
I'd consider my recent adventure up the grassy, unassuming rounded lump of High Tove in the Lake District as a QMD using the criteria in your first post. My plan was to head up there and on to Ullscarf from Armboth - access was closed "because of dangerous trees" so I had to plan a different route (route planning box ticked). I was on my own (leadership box ticked
). Because it is a grassy, unassuming, featureless lump, I practiced / fine tuned my pacing (so part ticked the nav skills box). It's in the UK (so that's the comparable UK terrain box ticked). As I ascended I realised I was running out of water and there were no streams to refill from - all dried up in the hot weather we're having (so that's the increased knowledge box ticked that hot/good weather needs to be taken into consideration just as much as cold/bad weather). My plan was to carry on to Ullscarf but I changed my plans due to the relentless heat/lack of shade and my rapidly depleting water (so that's the attention to safety box ticked). I was most likely out for more than five hours, though a lot of that time will have been spent sitting whenever I found a rock that had a bit of shade from the sun. I would say that, on that day, it was a 30 degree heat/no breeze (so that's the adverse conditions box ticked).
So, because I didn't end up on Ullscarf, does that mean everything I learned and practiced that day wouldn't count as a QMD?
Any day in the mountains ticks one or more box, in my opinion - even if it's an aborted mission because the weather was too nice