I do agree that unlike those for fun, pattern planes fly for competitions with predefined flying time, which is 10 minutes.

But time is not a measure of the electric charge that your motor pulls out from the batterey. More importantly, even for the same amount of electric charge being withdrawn from the batterey, you will end up with different final voltages every time.

Some discrepancies may happen during charging, for example when your charger stops earlier for some reason. Another example: some cells in the pack are not feeling well enough to take in the charge as much as they should and many other similar unfortunate cases. These all suggest that your 10 minute timer is not enough to protect your pack against deep discharge.

In fact, LVC is the first thing you must set properly even before considering timing and PWM frequency, which are just for optimization purposes. Almost all motors work with default timing and frequency. At least it will not cause any accident! On the contrary, if you accidentally have too high LVC setting, your plane may make an emergency landing on the high grass and you may have to fix her landing gear.

Another thing is about progbox.

Rather than relying on a progbox, why not just use a widely acceptable USB port and a PC/Laptop.

There is a tiny microcomputer inside the ESC and as always, microcomputer runs a software/firmware and as always, software contains bugs and revisions are always ongoing from time to time. By using USB port and widely used internet, consumers can download the latest software/firmware revisions and update their ESC via USB port. This way, vendor can quickly distribute some urgent fixes that are known after some problems reported from flying fields.

Unlike CG, wing incidences and thrust angles, setting ESC is almost never done at the field. This is because there is no field/flying evidences/data needed to set your LVC, motor timing or PWM frequency. All can be done at home. You will never need to bring in your PC/laptop to the field.