Background:
I'm continuing to work through MMAsherdog's BTS Ultimate Course and in the Blind vs. Blind video he shows a pattern that I don't understand. So the spot is SB vs. BB single raised pot. We range c-bet out of the SB on a rather dry K-high board that favors the PFR and get called. The turn is a broadway card, so a high equity card for the SB c-bettor.

Question:
Of course, after a range c-bet, we check a lot, especially oop. We still have a betting range though. What I noticed is that there are two different kinds of boards that lead to completely different sizes that we choose on the turn.

Board 1: KT4 Q
Here, the SB c-bettor goes for a small sizing on the turn. This makes a lot of sense to me since a high equity card for our range will lead to quite some betting (even after a high frequency c-bet OTF oop), and since a substantial part of our range wants to bet we go for a small size.

Board 2: K52 Q
This is also a high equity card for the SB c-bettor after a high frequency c-bet OTF, but now we go for a big size when we bet. Why? Across many regions of the game tree, I have whitnessed the rule of thumb that blank (!) turns lead to large sizes (and a lot of checking) for the c-bettor, whereas high EQ cards lead to a small size and a large betting frequency. If a substantial part of our range wants to bet, why not choosing the small size?

Attempt of an answer:
Maybe it's too simple to say that high equity cards will lead to a small size and blanks lead to a big size. I was recently told that

1. the equity of a card for our range determines our overall betting frequency
2. the polarization of our range determines our sizing

So could we maybe say that on KT4 Q, our betting range is less polarized since BB will also have AJo/J9o and the tops of our ranges are closer together? While on K52 Q, SB's nuts are uncontested and want to go big? This is my hunch, but when I check the equity distributions of SB and BB for both spots in Flopzilla, there is few visual difference in the tops of the ranges...

What's your take on this?