Thanks for replying Terry. Appreciated.
Over the last year, between doing my first 1km and my recent 2+km swims, my sessions have been pretty much exactly what you suggest. In these, my spl has generally been in the middle of my green zone and within 2 for a session.
Last week I tried the suggestions in your Guaranteed to Improve Stroke Length thread. I didn't get any variation in my spl doing that, bar a few exceptions it stayed stubbornly at 16 from the get go, but that was good as previously it had been 18. Maybe this was due just to having the TT so slow. Anyway, for anything more than 100m sets, I'm not sure if using the TT is helping or hindering me now though.
In my Friday 2.5km I wore no TT and swam the first km at 2:13 and 18spl and the last 500m at 2:11 and 20spl. Overall I did it at 2:13. After that I swam 250m with my TT set to 1.40 and the data for that was 2:16 and 22spl !! I was stunned, so I took the TT off and swam a set of 22 x 25m's, to try and correct whatever had gone wrong. My spl went immediately to 16, but I was simming slower than 1.40. The closest lap to 1.40 (maybe 1.50) I did at 18spl and just shy of 2:00.
My theory for all this is that the TT diverts my attention from my stroke which still is something I have to pay a lot of general attention to.
A psychological disorder is: "Any personal construction which is used repeatedly in spite of consistent invalidation."
~ George Kelly
"The water is your friend.....you don't have to fight with water, just share the same spirit as the water, and it will help you move."
~ Aleksandr Popov