I think there may be a point that is being overlooked and this applies to all aircraft.
If a battery is too discharged to make a start by a short term drain like leaving the master on while briefing, it will usually still have adequate capacity to power anciallaries once the engine is started. It also will often make a re-start immediately, but this is because the battery still has substantial capacity left and the engine is hot, not because it has re-charged in a few minutes.
If a battery has become completely discharged, by leaving the master on all night for instance, then it is a different issue. The battery (with a resistive load) will have no capacity left at all and may also be damaged. No amount of ground running in this situation will make the battery 'safe' from the point of view of capacity after an alternator failure or any load exceeding the alternator output because the charge rate is so low that hours of flying would be required first.
In my view a battery that is completely flat also presents a hazard to the alternator because the current limiting regulator designer may not have envisaged the battery being a short circuit with an unknown restore time. Outcomes could include the one described in this thread, total electrical failure and in flight fire in almost any aircraft.
A lead acid battery will often be designed for a 12-hour charge and while a shorter time (say 1-2 hours) will prove that the battery is still serviceable, it is cavalier to just jump start and hope for the best in my view. I'd think twice about doing that in a Land Rover, let alone a glass cockpit IFR twin!