The problem is, our environment we've known since the early days has changed while the interface has remained the same since UDS was introduced a couple of years ago, it might be more or less than that, I can't remember.
When UDS was introduced, N3V said that the recommended practice is to build in the route-building side of Surveyor and do all session editing in the Session-creation side of Surveyor. What this does is place the appropriate assets in separate layers needed to operate a route. The separate modes now cause a disconnect between the route and the session even though they are associated.
In the olden days, we built routes in Surveyor and drove them in Driver. If we wanted something permanent, we'd create a session to drive again. Then Universal-Driver-Surveyor (UDS) was introduced around the same time that multi-player Surveyor (MPS) was developed. In MPS you can build a route while other people are driving at the same time. This is quite an experience and I enjoyed my time with it during the beta. UDS allows a single-user, on their local Trainz install to jump directly into Surveyor and modify things you found while in Driver. In theory, this is awesome but it comes with its drawbacks such as saving the session while saving the route during a fix and we end up with drivers out of their starting positions with no way to reposition them again without editing the session. Going from Surveyor to Driver in UDS, which is similar to the old Quick Drive, is great for checking ATLS and other scripted assets to ensure that they are working properly, and to test consists such as those with pantographs to ensure that they reach the overhead wires.
In a nutshell, we now have to watch what we're doing and tread carefully and thoughtfully rather than just do what we were doing what we were doing all along.