Bready

My understanding was always that kneading/folding/rolling/etc. was done to homogenize the dough mixture to form an even crumb, and to align gluten chains to increase the elasticity of the dough and allow it to retain more of the gasses during the proofing process.

Whatever method you use doesn't really matter, and the time isn't as important as the consistency reached. Getting the dough to the point where it can form a stable loaf without being floppy uneven is the goal.

You can OVER knead dough, though doing that by hand is difficult unless your hands are used to doing a lot of work like that. Typically over-kneading happens in kneading machines that are run too long, and the end result is bread with a thick, hard crust and a dense, dry, crumbly crumb.

I'd heard that kneading "activates the gluten", but tbh chemistry was never my strong suit so I have no idea what that means in the real world. I suspect kneading time relates to the level of activation or resulting gluten level, or perhaps even the speed at which the activation occurs. I couldn't even tell you what gluten does in terms of flavour or chewiness or whatever.

I've just never found the right eli5 for me about it. Perhaps split a batch, knead one half and do a comparison taste test?

Kneading time depends on hydration. For a 50% hydration dough you need just a few minutes. For 65% hydration you need about 5-10 minutes. But a lot of people these days make even higher hydration doughs and kneading time can easily be 40 minutes of non stop hard work.

If you want to learn the feel, start with 50% hydration.

I've seen magic phase changes, but not every time. I make my dough in a stand mixer and it'll knead on the hook for 4 minutes with no change, jsut a gooey mess. That next minute it magically become tense and balls up and climbs the hook and I'm done. It's kinda funny.