What the page says, and what it does not
A price list that reads $89 every 28 days is telling you two things at once: an amount and an interval. The amount is easy to compare. The interval is where a comparison usually breaks.
Twelve 28-day cycles cover 336 days. A year holds 365.25. The gap is 29 days, which is a thirteenth charge roughly every twelve months. A reader who multiplies $89 by twelve gets $1,068; the year actually costs about $1,161. Winona's record is the case used here: $89 every 28 days, on the record at its check date.
Why we do not call it monthly
A 28-day cycle is close enough to a month that it is tempting to describe it as one. The guide does not. The charge is recorded with its own cadence, and the monthly figure is derived and labeled as derived.
This matters most on the pages where a program's sticker price looks lower than a competitor's calendar-month plan. On a like-for-like annual basis, the difference can reverse.
How to check it yourself
Take the charge, multiply by 365.25, divide by 12, then divide by the number of days in the cycle. That is the derived monthly figure used throughout the records. For a 28-day cycle it always produces a value about 8.7 percent above the charge.