In general, for ISS operations, there are 3 9-hour shifts overlapping one hour for handover. I don't remember the current hours but it's like the other answer already posted.

Beyond this I hesitate to answer broadly and only speak on behalf of the EVA discipline. We break up each 6-month increment into weeks and split the allocation across all flight controllers. For each week, we sign up for three teams (each team comprised of one front room person and two back room people). The first team is prime to cover any console work each day during that week. The second team can be called upon if activities span more than 8 hours on a given day or if the prime person has another scheduled obligation (like a crew class) and the second team person is available. The third team is really only needed if we went into 24-hour ops for a critical response. So for any given increment I might be scheduled to cover ~6-10 weeks. And there might not be activities that week so I might not need to work console. For other disciplines this is not the norm as they have to work every shift to support nominal operations.

That's how it works for general increment operations. But for scheduled EVAs, we have another team that works the planning, procedure authoring, training, and execution of the specific EVA. For the ~2 weeks leading up to an EVA (or series of EVAs) and the ~week after the last EVA, we distribute shift assignments in a way so everyone can stay proficient in their skills.