Not to be picky(
) but, actually the lower the SOC range is, the better for the battery. So the best range is not around 50%. As low as possible is causing the least degradation.
If you need 30% depth of discharge, cycles between 40 and 10% is better than centered around 50%( 65-35%).
Tesla instruction to charge asap if below 10 or 20% is most likely coupled to the risk if discharging the 12V battery and getting stranded.
All research show us that small cycles at low SOC is causing minimal degradation.