I'm in a similar boat to some of you - I run 1 hour later on Friday and Saturday. I just manually update the show daily. Additionally, I run an afterhours show. I am skipping 5 minutes (as suggested previously) between the two shows.
One thing you can do is just update the show definition. That way you don't have to re-create the schedule every time. I've changed my show layout 100 times probably as I both added and changed the order / voiceover frequency, etc. As long as you don't change the show name, you can update / modify the layout and not impact the schedule.
My two show names are 2012Main and 2012Late. Creative I know!