How do the Daily Chess vacation days work?

I was trying to toggle something in settings recently when I found a switch that could pause my Daily Games. It's called "PAUSE MY GAMES! I need to go on vacation", and it's in the Daily Chess settings at the bottom.

When I first looked at it, it said I had 11 days of vacation, but after I upgraded my account, it changed to 1 month and 9 days.

My first question is this: What affects the number of vacation days one has?

My second question is this: Why is the number of vacation days seemingly an arbitrary number? In other words, why not use standard units of time like weeks or months?

I doubt this question is of any importance, but I'm curious.

Thanks to whoever answers this <3

I think this article should help...

https://support.chess.com/article/624-how-does-vacation-work-how-much-time-do-i-get