My wife and I have been taking more, and longer, trips in our Tesla Model 3 LR (300+ mile) range car. This is windy season. I've learned the hard way that the more we talk about the nuances of range, the less secure she feels. She wants reassurance and KISS (keep it simple, smarty), not DIY tools or a dive (no matter how shallow) into the why's. The why's cause anxiety because they imply scenarios she may not be able to handle.
Her reflex is to be over-cautious and over-charge which is fine most of the time, but it lessens the convenience and practicality of the car which is its own problem. Fortunately the Tesla has really excellent dynamic range analytics built in so the message has become the following:
1. Tell the car the destination. Make it a habit
2. ALWAYS have a Plan 'B' to add charge, and preferably a Plan 'C' too
3. If the car says estimated destination SOC is below 15%, slow down
4. If the car says estimated destination SOC is below 5% and it is over 50 miles away, bailout to Plan 'B'
Her use of this device is pretty reasonable. She frequently checks the destination SoC until she convinces herself that it is stable. Then she relaxes. This approach could be problematic in a winter storm but we are not taking long drives in those conditions. As she gains experience I think she will adopt my approach of being progressively less cautious, and using up reserve as I near my destination although I still haven't come up with a non-numbers method she will find usable.