I planned three main sessions for Chamonix. I wanted to get up to 2500m altitude a couple of times after suffering a bit at those heights in the UTMB race two years ago and I wanted to have a look at the course over in Les Contamines which is, hopefully, the area where I will be going into the dark. That means I will have recced the final 4 hours of the route.
If you are sitting in the UK watching this video, probably in the chucking rain..... sorry ;-)