Selecting no day has the same meaning as selecting every day.
If you select both days of the week and days of the month, it requires both conditions to be fulfilled for the profile to become active e.g. selecting Mon,Tue and 11th means the profile will become active when the day is a Mon or Tuesday and simultaneously the 11th day of the month.
If you are unsure if you have specified the day(s) you require, click the Done button and you will see a verbal description at the top of the Profile Edit screen. You can click on this to try again if it's not correct.