TM3 by default has the working hours set to be Monday - Friday. However, some clinics work on a Saturday as the majority of patients are free then so this is where they could get the most business.
You are able to change the working hours set on your TM3. In doing this it will change your week view on the diary to only have this day for all practitioners.
If you want to have this set up, if you access your Settings > Diary > Scroll down until you see 'Working Days' you should see something like the image below.
To change the working hours, all you have to do is un-tick the days you don't work and have ticked the days you do work. So for example, if we set our working hours to look like the following;
Our weekly diary will now look like the following;