When driving through Germany on the highway, it's not unusual for gas stations to be 50km apart. Tesla has a supercharger roughly every ~100km in all of western Europe (much closer in dense areas), meaning you'll be on average 50km away from one at any point. Not much of a difference in how far ahead you need to plan.

https://www.tesla.com/findus?v=2&search=France&bounds=58.954...