Dough strength from machine mixing/kneading

I read but I don't always retain. I'm sure this was all discovered long ago and I am just "rediscovering" it now.

I usually machine mix my dough for about 10 minutes total, on speed 1 or 2 on Wifey's ancient Kitchen Aid mixer. That would be 8 minutes with starter, followed by 30 minute fermento-lyse and 2 minutes additional mixing to incorporate the salt.

Yesterday I turned the mixer speed up to 4 and used that speed setting for the whole 8 + 2 minutes of mixing time.

When I turned the dough out of the mixer bowl into my wooden bowl I noticed the dough was very stiff or tight, much more so than usual and maintained good strength throughout the next 6 hours of stretches, folds, resting, preshaping, final shaping and proofing before retardation in a large bread tin.

Since I was making a large tin (sandwich) loaf I didn't get to test the dough strength after turning it out of a banneton prior to slashing and baking. But the dough performed well for my intended purposes and in a few weeks I will try to replicate this in a free-standing loaf.

So regarding mixing at higher speed: Are my observations consistent with established techniques or just a fluke?

Thanks and best wishes. Dave