Menstrual cycle

I am in my mid-40s.

My periods have been regular so far, but usually with a 30-day cycle, and over the past year, they've been getting shorter, like 28 days, 26 days, 24 days, and so on.

Even if it gets shorter, it usually shortens until the 25th, why is that?

They say that as you get older, your menstrual cycle lengthens.

Is getting shorter also related to age..?

I do it once a month..