Video Sync: why do timecode frames increment at 0.8?

Hello video experts,

Why do timecode frames increment at 0.8?
I’m tinkering with the framerates in Cubase, just to get my grounds for a video project I’m going to work next year.

I set up the project framerate to 29.97 fps (non-drop). When I zoom in, I noticed something curious.

Why does the “1 frame increment” happen at 0.8? In the following image, you’ll see that the ruler goes from 0:00:00:29.79 to 0:00:01:00

https://drive.google.com/open?id=1SN4z4kINYYgLIYY93xBXZY5fENnFFmQ2

Also, the 24fps setting also increments one second at 0.8.

https://drive.google.com/open?id=18zmrRCoCjJ2HTTwtqHeaj19g160fOZL7

I checked in several of the framerate settings and they all increment one frame at 0.8. Why do timecode frames increment at 0.8?