Agree preconditioning is most useful in the winter. Two days this week it was 35 degrees C and I made good use of the climate setting vs. setting for preconditioning. With car out in the sun, although it says the car is at the desired temperature within a couple of minutes, it's not really that comfortable. I find it needs at least 10 min to cool down from the cabin overheat threshold of 40 degrees C if not more. If climate is turned off, within another couple of minutes it's back up to 38 degrees. 2018, Tesla roof shade but no tint.
In the winter, preconditioning works for the cabin and the battery. If I had one wish, it would be to have a one time option vs. having to choose All Week or Weekdays. I occasionally end up preconditioning the day after I need it which obviously wastes energy and battery cycles.