Summary: didn't happen.
I realized that I, ahem, forgot to mention this. It rained all day… and it turns out that once you abandon a principle ("I'm going to walk every foot of the way"), then rain makes for slippery slopes. There were good reasons for not hiking the whole way on Stage 4, but taking the bus then made it easy to take a bus down the last couple of hours to Vals on Stage 5, to opt for a shorter route with a bus connection in Stage 7, and then to avoid being fried in a thunderstorm during Stage 8 (OK, that one was probably justifiable… but it makes me wonder how on earth we managed to do the H2H without ever being in a thunderstorm during 91 days of hiking!). And it also made it easy to decide not to do a long hike in the rain this day.
Everyone else was happy, though.