Do you want to send a specific Sequence email only on a particular day of the week?
You can, and here's how.
Open your Email Sequence and the particular email whose send days you want to restrict. Click the On days dropdown.
Deselect the days of the week you want this email to not send.
That's it. Your changes will save automatically, but you'll need to publish the email for it to start sending.
Use the On days dropdown if you want to customize each Sequence email's send settings. If you want to restrict all your Sequence emails to the same days of the week, it's easier to update the Sequence's Email Sequence Schedule settings instead.
NOTE: If you've set your first Sequence email as soon as possible (via the Send this email setting) only on certain days (via the On days setting), the email will be delayed as needed so that it sends only on those days. This is even if your Email Sequence Schedule setting specifies more days than that.
Let's say you've set:
The first Sequence email to send as soon as possible on Sundays, and
Your Email Sequence Schedule setting to all days of the week.
If someone joins your Sequence on Friday, they won't receive its first email until the coming Sunday.