EM systematically going outside for top executives is an admission that the internal HiPo system does not produce leaders.
Leaders cannot be developed by placing them into random departments that they do not know and cannot lead, and by protecting them from any challenges.
Any time a HiPo might be exposed to a challenge that is not 100% guaranteed successful, the HiPo is suddenly transferred to avoid potential bad exposure.
The other major fallacy is that HiPos that exhibit absolute stupidity are not dropped off the ladder, but instead their weaknesses are covered up by threatening phone calls forbidding any mention in ranking sesssions. HR does not want to ever admit a mistake so protects the poorly performing HiPos and perpetuates disasters for years as the id--t moves around departments.
The HiPo system needs an external consultant to expose all the weaknesses. We need to produce leaders that have struggled many times in nearly impossible situations and not babied/protected golden child mo--ns from or current HiPo system.