"That last is certainly true enough for Masters, be they Sith or Jedi. Sith to maintain power, for the most part; while with Jedi, usually because they think their padawans aren't ready. Sometimes they're right, sometimes they're not. But at least they usually don't deliberately do things that get their students killed." Unlike the Sith, who often enough just shrug and decide the dead apprentice obviously wasn't strong enough and go looking for a new one.