Yes a quick summary from what I felt. My spl has always been below the the SPL graph, the 33spl for a 50m pool was always very comfortable so to get out of the comfort zone the TT helped a-lot to be able to move me into a faster comfort zone. Once I start getting under 1.0 on the TT then am not sure how long I could go with the 2BK with my fitness level at the moment ( thats something I will have to keep checking in on ). At around the TT 1.0 mark I then started to time the beep with the kicks as you pointed out in London, then the other thing was being conscious of a quicker recovery which I think in turn prompted a bit more snap in my catch which I was then able to cut a stroke out when I felt I was tiring.I would probably look at my numbers and see a SPL graph for me as 33 - 39 or 40. My next sessions will be to increase the distance say 3 x 500m with the TT down around .98 and keep the 2BK on one 500, and try a mix of the 2BK and 6BK on the other 500. and at the same time compare my perceived effort for the 3.
All the best with the OP coming up.......
Enjoy the rest when you can get it.......
All the best Jeremy.