Over the years, I have had several health care providers comment on the "textbook" length of my cycles. Aside from a couple of years in my mid-20s when I was working overnight shifts, and had irregular periods my cycles have always averaged 27-28 days in length, ever since I started having periods at age 11. Everything else about my periods, including the amount of flow, number of days of bleeding & spotting, and mild cramps, were also what would be expected and just about average.
The textbook pattern of my cycles gave me the false impression that, though the years were passing, my fertility was unaffected. I (wrongly) figured that because my period reliably came on time month after month that when it was the right time for me to TTC, I would become pregnant readily. (I had the same incorrect thoughts about my "normal" LH, FSH, and E2 values and antral follicle count.)
Even though I now know that my textbook cycles only created an illusion of fertility, I was still glad to see their return this month. AF arrived on Monday, making my most recent cycle 27 days long. Because my last two cycles were 25 and 22 days long, I had begun to fear that I was starting menopause. Now I am reassured that all is well.
It may be a false reassurance, and I do have to wonder how useful regular cycles are when they never result in a lasting BFP, but for now, I'll take it.