Hi, dear E-Hamzeluyi. :)
Thanks for your remark. Yes, that's right, if they( English speaker) are speaking about the days of the week/month with even or odd numbers(dates), they use " even/odd days".
For example:
1-I should take this pill on even days and this one on odd days of the month.
2-Vehicles with even last digits on their licence plate drive on even days of week and those with odd numbers on odd days of the week.
3-They operate on odd days of the week (1st, 3rd, 5th....) in February and March.
PS:
By googling "even/ odd days of the week" I found that they might be used by non-English speakers like the following phrases and by specifying the days of the week:
On odd days of the week (Monday, Wednesday,and Friday)
On even days of the week (Tuesday, Thursday, and Saturday)
Like in:
1-Basically, on even days of the week, i.e. Tuesday, Thursday, Saturday you must park on one of the road.
2-In this case one parent is instructed that on even days of the week (Tuesdays, Thursdays, and Saturdays) she or he is to be completely in charge of parenting ...