Concerning the fact that razors of a seven-day-set mostly are marked "Monday", "Tuesday", "Wednesday"... does not speak for the barber's theory.
A seven day set surely was a luxurious thing as Glen pointed out. Most people probably had one or two razors and that's probably fine.

I have, however read a post - somewhere here - saying that they actually watched the burr recovering to some extent, when giving it some time of rest.
If that would be a fact, I wonder, if it is then a good thing to strop the blade after shaving.

I really can't say if it belongs more to "fables and myths"... But Glen was right, it is at least a good excuse for more razors.

Thinking about it, to be really sure that my burrs feel well, I should establish a 365 day rotation, yes 365 sounds safe enough.