Right now if you're on a road trip during a high traffic day the optimal strategy is to charge to near 100% at every supercharger because that will give you more options on your next supercharging location just in case those are also congested. Tesla has tried to solve this problem by by dropping the default charge percentage at congested superchargers to 80% but of course you can always set it back to 100%. My idea is that when a supercharger is full Tesla should offer a discount on your next supercharge session if you leave within five minutes or before reaching a 60% SoC.