28x13 = 364, add New Year's Day as an extra day, and New Summer's Day every 4 years, and we could have had a 28-day calendar all along, simply by agreeing to 13 months in a year (there *are* reasons not to, largely related to 13 being prime, but the weeks would still be 52, plus one day that is left out of any week, so seasons could simply be 3 months and one week each).
Dare to be rational, Runey!