Those of us who played Train Simulator know what I mean. The feature was simply, but it was also flexible and very quick to set up. I miss it in TSW. Timetable mode is nice, it's pretty quickly to get into, but it doesn't offer much flexibility. You can't just drive any train you want, you can't select start/destination. The new scenario editor does allow much more flexibility, but it takes time to set up, especially when you want some AI trains. A Quick Drive mode, like Train Simulator has, would combine the best of both. They'd be as easy to set up as a timetable service, but would offer the flexibility of the scenario editor. Just select the route, select the train/consist, select starting and end point, select time of day and weather, and off you go. Let the computer generate some AI traffic.
I think that scenario planner is pretty much a Quick Drive. Just with the exception of you having to plan the other AI. If this was Computer generated, then it would literally be a quick drive. I am hoping for a Timetable Planner.