I think of it this way. In all of my previous ICE vehicles, I would plan/budget so that I would refill with 2 gallons of gas left in the tank, but of course, sometimes, it could run lower to 1 gallon. My last ICE had a 16 gallon tank(BMW 330xi), so basically I planned to refuel at 12% SOT (state of tank), 2 gallons divided by 16, but ran as low as 1 gallon, so about 6% of my tank.
I don't see any reason to change the buffer for my Tesla, seeing as my last ICE was rated for 16/20mpg EPA, meaning that the 2 gallons gave me range of about 32 to 40 miles. In my Tesla, I plan for 15% SOC to refuel, and destination for 10%. That's approximately the same amount of miles available.
Yes, I know there are more gas stations than Superchargers. Yes, I know BEVs are more affected by temperature. Once, you get adapted, you make mental adjustments. It's no different than switching from a Prius to a Porsche, you have to adapt to the vehicle.
In my Tesla, if I'm going on a trip, I take a look at ABRP, and put in the best data possible, ie my speed, and coldest temps I expect. Then when I'm on the trip, I have ABRP open, and logging my car's real data, and updating whether the battery usage is going to plan. If not, I adjust. ABRP sees my real temp from the car's sensors, so it's updating the estimate all the time. The only significant variable impacting range that ABRP can't get from the car is windspeed and direction. I can look up windy.com to get a sense of the overall situation, but even if I don't, ABRP is constantly updating the live estimate. As far as I'm concerned, 15% SOC to get to a Supercharger is enough cushion, you just have to keep track of the dynamic situation and adapt accordingly. I don't want to run too low and cause any anxiety, but I also don't want to waste time charging when I don't have to. So far, in 2 years, I haven't ever had any anxious moments. YMMV.
Actually, I drive my BEV "3" exactly the same way I drove my ICE "3". I stop the same places for coffee, toilet and fuel. Trips take me the exact same amount of time. I've been going between Maine and Boston for 50 years, and believe me, it's the exact same time with the exact same stops, and I run the tank down to the same approximate levels, 12% to 15% SOC/SOT. It's the reason why I got the BEV "3" when I did, and not an "S", earlier.