thanks for the comment here. Based on your reaction, though, I think maybe I didn't explain my comparison between the two practices well. I am not at all against training with higher SPLs and higher SR, though as you say that has not been my main focus lately.
My normal TI sessions actually cover a pretty wide range of speed and stroke length, so despite my feeling of a loss of control/technique in the non-TI session, I was not swimming faster than usual (longer repeats, but not faster). My SPL pyramids in a normal TI session usually end up at 16 SPL on the upper end, with a :41 or :42 for 50m. Occasionally I go to 18 SPL, which on a good day brings me in at :39 or :40 for 50m. I get those speeds by CHOOSING to increase SPL.
During the non-TI practice, I purposely resisted my instinct to manipulate SPL in such a controlled fashion, and just tried to "swim fast." What happened was a much greater increase in stroke rate, but also a big increase in SPL. I was probably swimming 20-22 SPL for :40-42 per 50m on the fast legs.
So, similar speeds, much higher SR and SPL in the non-TI practice, and MUCH greater perceived exertion in the non-TI practice. The only difference was in the TI practice, I was consciously controlling variables and swimming mindfully. In the other session, I was focused only on "swimming fast" in a vague sense, without a specific plan about HOW to swim fast (i.e. increase SR without letting SPL get outside my green zone).
You said this, which I totally agree with:
You can work toward perfection in your sprint mindfully just as you can work on perfection on a lower effort level.
I can't read minds, so I don't know for sure how mindful the non-TI people I trained with were in their approach to their session. But based on conversations I've had with them and other non-TI triathletes at our pool, they seem to focus only on the clock and the desire to "swim fast" without a mindful and deliberate plan for gaining that speed. They do not seem to have a repertoire of focal points and subtle adjustments in timing and technique--they just "swim fast" (usually following a pre-printed workout rather than an individual plan that focuses on HOW to hit the speed you want).
I'm convinced that mindfulness is the key, whether it's officially TI or not. But TI provides lots of guidance about WHAT to be mindful about, and it certainly suits me!