From my experience of travelling across France during the TdF (and pausing to ride the bikes whilst getting paid on the way to Italy).
The travelling spectators migrate from each days stage to the next stage after the roads are opened, the keen ones that want a prime spot are the quickest to launch. Parking and behaviour standards on the night before the race goes through are interesting, many get moved on! Day spectators add to the chaos.
Roads used for the race are closed on the day for the publicity Caravan through to the race going through, and only re open after the broom wagon.
Following a day behind the TdF is no problem - everyone has buggered off!
On the day of the race in the area traffic disruption is to be expected from diverted traffic being forced to take a a diversion, allow spare time.