Having to "plan liberally" is something that makes EVs much less usable on long trips. When road tripping, its fastest to arrive at a charger with a very low state of charge (way less than a 50mi buffer). When I road trip my Model X, I trust that the supercharger will work, and I target arrival at a 3-5% state of charge. This allows me to charge at the fastest part of the charging curve, and to depart when the charge rate starts to drop off.

I have road tripped well over 10k miles in my Telsa over the last 5 years, and I've never seen an entire supercharger site offline (like happens with EA). I'm sure it must happen after natural disasters when grid power is cut, but its not the normal state of operations like it is with EA.