[IgorPartola]

This. I have been thinking about this for a long time. Basically, 364 days are exactly the same, and what is currently December 31st would become the Year Day where everyone has it off. If it's a leap year, there'd be two Year Days. Simple, efficient, and easy to understand.

Birthdays being on the same day of the week is a poor objection: your birthday already falls on a weekday much more often then not, and chances are you celebrate it on the weekend before or after. We'd lose variability in holidays that are "last Thursday of the month": they'd just be on a specific date every year.

One nice thing we'd gain is that the phase of the moon would shift much slower with respect to our calendar (the moon doesn't do a Year Day). I suppose some superstitious healthcare workers might object to this. If you think about it, there are many more things naturally tied to 28 days than 28/30/31.

[beefman]

Actually the synodic month is closer to 365/12 days than to 28 days, so the 13-month calendar drifts slightly faster with respect to phases of the moon.