I would agree broadly speaking David but it just appears to me that when models are showing mobile westerly unsettled conditions they tend to verify far more frequently than when they are showing something more settled. Probably because the prevailing westerly/south westerly is almost always the default setting and the models handle this setup much easier. Certainly I always feel more confident in the models when they are showing this type of pattern as invariably they all handle it pretty well and usually once this sets in it tends to stay set in for a considerable period of time which certainly appears the case at the moment sadly.
What I have found interesting about this summer is the way the jet has behaved. For all that southern areas had a generally better first half of the summer than further north, there were occasions even during this period when the jet dived south and brought noticeable rainfall to southern areas. I can recall at least three occasions during June when my area had rainfall from LP that had moved up from the SW, S and SE. This probably explains why Edinburgh had such a wet June, as was evidenced by the numerous posts in the summer moaning thread by John and Crespular Ray who both live there.
To my mind, the models seem to do best when there is either a straight west-east atlantic driven pattern that you mention above, or there is a very settled spell with a large anticyclone either over or near to the UK. From what I remember, the models were pretty consistent back in July 2013 wrt the development of the nationwide heatwave we had that month and it's longevity, and also the way in which it eventually came to an end. Perhaps the jet during that summer was rather less active that it has evidently been this season thus far and was a factor in why HP came to dominate during that particular month.
Lenzie, Glasgow
"Let us not take ourselves too seriously. None of us has a monopoly on wisdom, and we must always be ready to listen and respect other points of view."- Queen Elizabeth II 1926-2022