Nope, it's the reverse. They just start tunnelling without creating any voids for the stations. (As I said above, they excavate and pour concrete walls demarcating the ends of the station). That creates one long stationless tunnel.
For Crosstown, they came along afterwards and excavated downwards, to expose and remove the tunnel shell where the stations were to be built. Or they mined from below.
I believe I read that the Eglinton West TBM will be run from one end to the other. With Crosstown, there were three campaigns, one from each end, and one in the middle. The eastward TBM's were extracted on one side of the Cedarvale station and reinserted on the other, to avoid tunnelling under the Line 1 station.
- Paul
PS - I'm feeling really old writing this... it has been so many years since Crosstown tunnelling began!