Do I have to come for the entire four hours?

No. And yes.

Rev. angel understands the unique value of having periods of returning to meditation practice over and over again. The Half-Day SIT is intended to provide a container for that kind of extended practice. You can just drop in lots of places. The key word here is extended.

That said, this time is for you. The strong encouragement is that you try to come for at least two hours. If you cannot, choose to be in integrity with yourself and come for whatever period of time you can.