While it depends entirely on personal opinion, I believe that it helps significantly. It helps build up the problem/solution from the ground up and he goes through each step out loud to help a student understand. I get that some people hate it and think it is so childish for such simple steps. For other people, it helps a lot. Learning on KA works best if started aat a young age and done consistently (you get used to the style and you learn everything from the ground up).
In my case, it's not so much that I find it childish, it's that I find it incredibly distracting which means I can't focus as easily on the content. Instead of "oh, now I understand how that equation works" I catch myself thinking "why is he repeating the same word over and over - that's so annoying!". Then my brain starts obsessing over "when is he going to do it again?", even though I don't want it to. It's a bit like trying to deliberately ignore something. It becomes all you can think about.
Oh ok, got you. While it entirely differs on how different people receive ideas, for me, I just try to keep the end goal in mind (what are we ultimately moving towards) and just think of those repeated words as just small steps rather than just annoying repeating word.
YMMV but I found the style very helpful