Looking on the internet deeply has found these results:

on workdays is the most popular phrase on the web.

during workdays 129,100 results on the web	on workdays 1257,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
I'm not asking you where you were or why you can't follow an instruction like keeping your pager on during the workday.	Minute the workday ends on, 0 to 59. Don't take the stress of your workday out on me. Don't take the stress of your workday out on me. A lot of rich men just like to have a pretty girl around while they drone on about their workday. Activities described for day 3 should be performed daily (at least on workdays). Hour the workday ends on, in twenty four hour format, 0 to 23 I'm not asking you where you were or why you can't follow an instruction like keeping your pager on during the workday.

during workdays

129,100 results on the web

on workdays

1257,000 results on the web

More popular!

I'm not asking you where you were or why you can't follow an instruction like keeping your pager on during the workday.

Minute the workday ends on, 0 to 59.
Don't take the stress of your workday out on me.
Don't take the stress of your workday out on me.
A lot of rich men just like to have a pretty girl around while they drone on about their workday.
Activities described for day 3 should be performed daily (at least on workdays).
Hour the workday ends on, in twenty four hour format, 0 to 23
I'm not asking you where you were or why you can't follow an instruction like keeping your pager on during the workday.