The devlopment takes place on the location the currently regular working times. At the end of the working day, the tasks and source code are taken over to the team residing western to the current team. They do the follow-up work and move over their tasks and work the the next team. Theoretically, it can be worked much more on a software development project in one day. This kind of work needs a very good team management.
Sometimes FTS is used a kind of shift management, e.g. for 3-shift operations or 24/7 support. The shifts will be divided and and distributed globally. Nevertheless, originally FTS is just meant for software development.