That's how long it takes to cover a wall with chaux-chanvre.
Unfortunately, because of the nature of the beast, it is something that needs to be done all in one go, because if you stop for more than an hour the end result is patchy. As we are hoping we can leave that wall "au natural" it means that patches are not an option, and once he started, there was no way Stéphane could stop.
This morning, the wall looks like this, and should continue drying out for the next couple of months until it is almost pure white. You can see how wet the chaux/chanvre mix is by how much moisture has leeched into the staircase.