Different working hours for each day
It'd be useful to set different working hours for each day on the week.
for instance, on fridays I work from 9am to 3pm. But the rest of the week I work from 9.30am to 7.00 pm.
I thing this is useful since nowadays people has flexible timmings, working from home etc. It's important to set the times you are available for meetings each day so coworkers don't schedule any activities when you are not working.
S. Harms commented
Provide an option to customize daily work hours in the calendar. Everyone have different working or office timings. It is odd to think that Outlook forces you to use the same work hours as provided in the Outlook . Also Calendar should have workday option for scheduling meetings. There is no option currently to set recurring meetings on a specific workday.