1LA’s for the Days of the Week

You’ve all seen it: The days of the week abbreviated to a single letter, done as so:

   M  T  W  T  F  S  S

Really?  Two T’s and two S’s?  That’s rather lazy, and ambiguous!  Here’s the better way:

   M  T  W  R  F  S  N

You’ll see that thuRsday uses an “R”, and suNday uses an “N”.  Much better!  By the way, I know from personal experience that this better system has been in use for over half a century. Have we forgotten history again?