1) Everyday Driving / Commuting: Much like an ICE vehicle where one thinks about 1/2 tank, 1/4 tank, etc... we think about percentages. For us, a round-trip to the in-laws is 50% in the summer and 60% in the winter, for example. Commuting round trip is ~15% in the winter, and ~12% in the summer. This combined with the fact that the car starts every morning charged to 80% means that we really don't ever worry about super charging in our day-to-day life.
2) Road Trips: The navigation software on the tesla automatically add charging stops where needed, and critically, it is very accurate when predicting range as a percentage when it knows your destination. We typically charge until it say we'll reach our destination/charging stops with 10%. That reserve has always been more than enough even on 1000 - 2000 mile road trips.
My general advice to anyone with a Tesla who has range anxiety: 1) Put the round trip into the trip computer. (e.g. Home => Place I Want To Go To => Home) 2) Always make sure you'll get to your next charging stop with 10 - 15% left according to the trip computer. 3) Relax and enjoy the auto-pilot :)