not sure it applies here as i do not use CMC but rather an add on tool for some scheduled reports using Windows scheduled jobs, but just in case it helps...
I add in extra crystal select statement options to compensate for hourly reports taht I only want tro run on certain days. This makes the report return no values so it technically runs but does not get sent out because it has 0 results.
For weekday only reports I use:
weekday(currentdate) in [2,3,4,5,6]