Time-management is probably the single most important skill in these higher-paying jobs and...well...given the amount of self-help books there are on this topic, I'm not so sure I'd agree.

People who do well in higher-level jobs know /exactly/ what they're best at or uniquely positioned to do, and do that. Meanwhile, you need to delegate the rest to whoever's in the best position to do so (growing people if there aren't enough) which is itself a tricky calculus.