Running a timetabled service is the reason I have a layout, and most of the models, and why DCC was such a natural choice.
Same as Alastair though, I would suggest a sequenced timetable, with the rate determined by the operator rather than a clock. The simple fact is that if attempting to perform what were fairly brisk operations on the real thing (e.g. reversing a steam suburban service including relocating the stock from arrival on down slow, across the ECML fasts, to the up slow platform or bay) you cannot use a speeded clock, it is a real time operation. You might 'pinch' 20 or 30% of the time the prototype required, because you don't have to wait for the section to clear, and can run much closer headways, but that's about it if observing realistic speeds for the movements.
So then you just sequence the other movements that are run throughs or stops but without any shunting in turn, and as Alastair says you can pick it up and leave it without any further to do.