Looking on the internet deeply has found these results:

days of the week is the most popular phrase on the web.

days ofa week 1558,000 results on the web	days of the week 156,200,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	These are blister packs showing the days of the week. All you got to do is sing the days of the week and be famous. Well, it's Tuesday, and I know how you forget to eat breakfast on Tuesdays 'cause the first few days of the week tend to confuse you. (the days of the week will be printed on the foil in abbreviated form). We need to get you one of those pill organizers with the days of the week on it. He didn't know what a burr hole was and he messed up the days of the week. He renamed the days of the week. A reliable source later informed me that these double checks are applied on certain days of the week at Terminal 1B for flights to the following EU countries: Bulgaria, Poland and Romania.

days ofa week

1558,000 results on the web

days of the week

156,200,000 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

These are blister packs showing the days of the week.
All you got to do is sing the days of the week and be famous.
Well, it's Tuesday, and I know how you forget to eat breakfast on Tuesdays 'cause the first few days of the week tend to confuse you.
(the days of the week will be printed on the foil in abbreviated form).
We need to get you one of those pill organizers with the days of the week on it.
He didn't know what a burr hole was and he messed up the days of the week.
He renamed the days of the week.
A reliable source later informed me that these double checks are applied on certain days of the week at Terminal 1B for flights to the following EU countries: Bulgaria, Poland and Romania.