Good post TarTripper, nice little wake-up call and I'm glad I glanced at it.
What occurs to me is that you may well have got in a wee bit hot like this on several or many or even countless previous occasions but there was no-one coming so you got on with life.
If you enjoy that sort of riding - and I have and still do on occasion - then such moments are all but unavoidable, IMO.
The reality is, they are also very hazardous.
So then the question is, how to reduce their incidence.
Only obvious answer is to slow down a bit. A secondary one for you might be to notice that after an hour or so of high-level riding you get a bit fatigued. Makes sense to me and I'm sure I'd be the same. I will take that on board.
I am not quite sure what you are trying to say about target fixation, but it seemed to me you were proposing - from the benefit of this experience - that in some high-stress, unfamiliar moments it is quite likely a person will not be able to avoid target-fixation.
That makes sense to me, too.
Sorting out the S4Rs Ohlins shock: click here