Fwiw I find their meals take me less time just because left to my own devices I tend to make more complicated affairs.
However your comment about preprepping everything, aka mise en place, actually does improve your cooking experience in the long run once you get used to doing it. Sure some things you can multitask on but it's not always possible to say how long it'll take you to chop up that garlic and maybe you timed it wrong
Anecdotally I disagree with mise en place. Chopping all the things and then putting them in a separate bowls to be used later has never been faster for me than chopping things as I need them and throwing them into a pan that is already cooking the thing I just chopped.
I theorize that all recipes are written with mise en place in mind because many recipe writers have experience in the restaurant world and that is how things are done there. There is a prep time to chop everything before the busy times and then when orders come in they can quickly fire all the chopped ingredients, so the actual cook time to table is fast when time is most important but the overall time is slower, but it does matter because the prep time occurs when people are not waiting for food.
Again this is all theory and I could be super wrong.
You're absolutely correct that a true mise en place, for most dishes, is more of a hyperoptimization for people who aren't cooking on a line. Things like quick stir fries are an exception, mind you.
I started, as most people do, prepping as I go. My cooking sucked. Not just because I prepped as I went, but partially so. I'd get to step 3 and see for step 4 I needed chopped onions, so I'd start chopping onions. But step 3 was supposed to cook for less time than it took me to chop onions, so step 3 went on too long. In this sense, a full mise en place helped me get better at the actual cooking parts.
As time went on I developed better cooking habits. I'd understand the full recipe prior to cooking. I had a better body of experience to estimate how long chopping those onions would take so I could plan ahead on if I should be doing it ahead of time or while some step < 4 was going on. I also had a better conception of the economies of scale in that perhaps it would be faster prepping items A, B, and C at the same time instead of separately but item D didn't matter.
Once you get to that point I think you're absolutely correct in that a hybrid model is better overall, but I think one needs to go the full mise en place route first to develop better cooking chops (pardon the pun) prior to going that route.
However your comment about preprepping everything, aka mise en place, actually does improve your cooking experience in the long run once you get used to doing it. Sure some things you can multitask on but it's not always possible to say how long it'll take you to chop up that garlic and maybe you timed it wrong