I've never said you can't ever mow at full sticks, You can, but the conditions need to be right. For Mick, it's short and dry with the stiff turf he has. For you, you just laid out a bunch of conditions in your post for it.
I have said, and will stand by it too, that you can't do it for every day, anywhere mowing. The math doesn't lie. Unless conditions are ideal or as close as we'll ever see on this planet, there's going to be missed grass/stringers.
I've mowed at full sticks on my mower when the conditions allowed, and while it may not be 15 mph, it is supposed to be 12 mph and the QOC is nowhere near as good as it is at around 6-8 mph due to many more blade strikes per inch at the lower speed. It may have looke dalright to anyone else, but I can clearly see the difference between the two speeds.