As you can see, there are 13 months with 28 days and 1 day (on leap year this is 2 days). Now I'm a bit of a socialist in heart so that 1 day (or 2 on leap year) I would count as a month so we get 14 salaries. It's a win-win situation. Clean and simple.
I’m aware of this calendar, but it’s still inspired by old popes:
> Since Cotsworth's goal was a simplified, more "rational" calendar for business and industry, he would carry over all the features of the Gregorian calendar consistent with this goal, including the traditional month names, the week beginning on Sunday [...] and the Gregorian leap-year rule.
The Gregorian reform was mostly to keep Easter in Spring - the Computus of Easter being the most important calendar consideration of the time.
Edit as time has passed, other considerations, such as industrial uses, have taken precedence.
Here: https://en.wikipedia.org/wiki/International_Fixed_Calendar
As you can see, there are 13 months with 28 days and 1 day (on leap year this is 2 days). Now I'm a bit of a socialist in heart so that 1 day (or 2 on leap year) I would count as a month so we get 14 salaries. It's a win-win situation. Clean and simple.