In the revolutionary context, the extra days were all piled into the end of the year. Kind of a special short month, or more realistically a set of days not in a month. But yeah, leap days were added there when necessary.

Twelve months of five weeks of six days plus five or six days at the end for Christmas and New Years would absolutely rule. As long as weeks became 4+2 and not 5+1, anyway. I say we drop Thursdays and just keep the rest of the day names, they’re fine.