First off, good job at Tempe. I did the race last year where the swim was long. This year it looks as if it was correct.
But as for your swim, I believe you know the “real” answer. And it has nothing to do with what you asked, ie. set intervals and distance ramp-up. The answer is total technique focus. I mean total, full court press. And from where you are at, coaching.
I too like most have been frustrated with a lack of improvement compared to the time invested. But with hope and commitment, progress does come, albeit incrementally. There is not one swim I ever do without thinking on technque. Even in a race. This past Saturday hit the ramp in 23:30 up in Utah. For sure my best swim so far. With more improvemnt to come. And for the most part solo, with my nose in the “wind”. I couldn’t stay with the lead out, but that doesn’t bother me if the “right feet” are not in front of me. I am confident going it alone if need be. That’s where you got to be.
Yesterday went to the pool. Of course for an easy swim because I’m in recovery training for awhile. A group of swimmers who swim there on their lunch break were there. One of them who I know is the best triathlete in town. He is one of those freaks, who maybe races a Triathlon twice a year. Ex-division 1 distance freestyler out of Utah. A real freak like I said. Races Rage this past April and goes wire to wire off the front for the Overall. Anyway, I’m walking along the deck and he calls me over and gives me a few tips. Then demonstrated my stroke. All I can say is, “I splash so much on my entry”? Now I have been working for a long time on cleaning up all those types of flaws, but until someone shows you the flaw, ever so vividly, you just don’t "see"it.
Thought about it while doing my easy swimming and drills (he said do some catch-up). In my focus this year of max extension and tempo, I had become too shallow on the recovery and entry, and hence, too much turbulence and slapping going in. So the focus now will to be to come in at a 45 degree angle and then extend, smoothly to full extension.
Drag forces increase exponentially as one’s swimming pace improves. And so must one continue with technique work, even as one surpasses one’s highest expectations, of what one thought possible, say a year ago. The work must always continue in this fashion. That takes precedence over set construction.
Stick with it.