If I may interject...
I totally agree with Snoopy, if I had socks marked with the days of the week I would feel compelled to wear the correct day's socks. (but then I am a bit OCDish)
Thank God for that!
Once you have worn the socks of the day, each will be slightly stretched by the respective big toes.
When next you have a 'Monday-sock' day, do you:
a. Ensure you put them on the same feet to keep the toe-stretch in the same place.
b. Alternate them so both have balanced toe-stretching.
This principle applies equally to socks that are not calendar-marked of course.