If you feel like arcs take away from the regular comic you can try putting arcs on a separate page and keep the "regular" comics on main page. You can advertise the arc in the sidebar like "Isaac: Satan's Game Part 7" to attract people there.
Is it a problem to make small breaks in the arc? You update the comic multiple times per week so it shouldn’t be a big deal to skip one day and post something different when something big happen would it?
