We had more fun in 2 or 3 cars, driving the route we had planned and finding hotels when we were tired.
Driving set distances is fine but without driving the route beforehand on a recce it's impossible to gauge by TomTom and MS AutoRoute how long the actual driving will be and that was a major complaint from the last couple of years - that some of the stages were way too long and had people arriving very late at the hotels having spent 10 hours+ driving. The motorway sections are relatively easy, it's the mountain routes that are so hard to guess as there are so many variables (weather conditions, road closures & detours, average speed, strength of people's bladders, people's map reading skills, even down to road surface quality)
Plus in small groups you attract way less attention from le flick, so you can press on relatively unnoticed. In a large group of the same make/model of cars it draws a lot of attention