Another four today:
9 Chickweed Lane by Brooke McEldowney
Non Sequitur by Wiley Miller
Overboard by Chip Dunham
Pearls Before Swine by Stephan Pastis
Frazz should count --but for the minor technicality of the silent panel not being penultimate.
Chip Dunham is this week's champion with three uses of the silent penultimate panel.