a flailing, loping conner mantz becomes a tight, refined conner mantz not by getting fitter (he was already fit as a HS soph) but by observation and immersion into a cauldron of runners who're better than he is.
..
swim strokes are, to the eye, quite variable, but most share common best practice elements.

Yes, they do. For the same reasons cyclists do. They're faster.

Sorry to interrupt this discussion on cadence, stride length and form vs "efficiency", but I was wondering if there is acknowledged evidence that some particular form (more than others) results in reduced chance of injury?

I mentioned earlier in the thread that I am trying to heel strike less because I've broken a bunch of bones and had some other minor injuries over the past 5 years, all from running.

To be honest I would give up a few % of efficiency to keep me running all year round without any interruptions.

I know there are other things (strengthening, rolling, etc) that can help prevent injury but I am talking about isolating form as an independent variable for injury prevention.

Conner also grew older, stronger, and did lots more running plus numbers of workouts that he hadn't done in HS. It would be difficult to separate the effects..

Your 440yd repeat story does bring up an interesting point - it seems to me there is room for technique coaching in sprinting. Though this is just idle speculation and I haven't studied it in any detail. A brief jaunt into the research - it also says speed is optimized at self-selected stride frequency..
Distance running however is about optimizing efficiency and economy, nothing does this better than running. The study linked concludes, "trained runners chose a stride frequency closer to the optimum for energy expenditure than novices. "
Were they coached into selecting optimal stride length ? probably not..

Entirely agree about the swim strokes - except that the variability is mostly when watching from the deck. Underwater video tends to show that fast swimmers' strokes are more the same than they are different..
And here we are talking about a learned and not well understood adaptation to hydrodynamics. No-one knows how to swim, they have to be taught, based on a selection of randomly evolved strokes (how did we end up with the crawl, anyway ?). Then hydrodynamics sets the rules and we have to obey.
But the first thing everyone does after learning to walk, is run..

Generally I'm all in favour of study and optimization via practice, have done this all my life in the learned sports like flycasting, canoeing, etc. But distance running isn't a learned sport..
Now it seems to me I'm making a sort of Paleo Diet evolutionary Just-So-story argument for run training, which heaven forfend. I'll have to come up with a way out ;-)

i don't think there's a lot of space between us. swimming is exactly analogous to running in this sense: there's a ton of variability in what doesn't matter. there's very close conformity in what does matter.

one thing that doesn't matter is stride length. it's not of direct interest to distance coaches. it's not one of the things that does matter. so, measuring stride length, and demonstrating that coaching form is useless, is like measuring distance per stroke in the pool, among both novices and elites, and concluding that coaching swim form is useless.

but what does matter, in running form? in swimming hydrodynamics requires certain body positions and stroke form. There's nothing analogous in running. No-one (cf Daniels experiment) can identify good running form. There is no evidence to show alterations in running form produces either faster runners or fewer injuries (with caveats as per my injury post above). If there is I'd like to see it.

you asked me what the tenets of good run form are. and then you write, adamantly, that there's no such thing as good run form. you've learned everything there is possible to learn about running. you don't need an guidance from me.

sorry, I am not making myself clear.
1. For every example of what is described as 'good run form', there are multiple fast experienced runners who do not display the attributes of that 'good form'.
2. Those that can see 'good form' cannot teach it - at least in my rising fifty years of following running and coaches and exercise physiologists, I've not yet seen a case where form adjustment alone led to better performance.
3. 'good form' considered harmful - as per points 1 and 2, forcing changes to run form is not likely to help and may produce injuries and slower performances.
Point 3 is the one that matters, and the only reason I get into these arguments.. I know I can't win, but at least some bystanders might get some food for thought. Peace out..

And this.....

https://www.outsideonline.com/...-worlds-best-runners

"Of the 70 runners analyzed during the fourth lap of the men’s marathon, 47 of them (67 percent) landed on their heels, 21 (30 percent) landed on their midfoot, and two (3 percent) landed on their forefoot. The percentages were similar in the 78 competitors analyzed in the women’s marathon: 57 (73 percent) heel, 19 (24 percent) midfoot, and 2 (3 percent) forefoot. And this pattern wasn’t confined to particular countries or finishing places. In the men’s marathon, the top four finishers, hailing from Kenya, Ethiopia, Tanzania, and Great Britain, were all heel strikers during all four laps of the race.
This is particularly interesting because the idea that elite runners don’t land on their heels is so pervasive. When Nike was developing shoe concepts for its sub-two-hour marathon project, they at one point produced a prototype with the heel mostly stripped off to save weight. The problem was that virtually all the elite runners who tried it hated it, so they ended up pivoting to the chunky, cushioned heel in the new Vaporfly 4% shoe."

Glad someone put this stuff out again, thanks!

Even though this has been documented many times there seems to be a continued call by the no to low drop fanboys & girls to change your run form.

Most people would be better off running more & thinking less.