I thought it was more recent than "centuries old". Wasn't it stated somewhere or other that the catastrophic burnout at such a young age was mainly due to using magic engines? So that without the damage to her magic talent from the engine's supercharging, an average witch would keep more of her powers for longer? This would explain the presence in canon of a few older witches who still have some amount of magic; they were trained and went through most of their working lives before magic engines were developed.

(I've seen but not yet bought the Fuso Sea Incident manga, where the magic engine was in a big bulky backpack instead of integrated into a Striker. Was this older technology more or less likely to produce burnout, I wonder.)

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