Reason No. 4: Retention
Managers with training tend to have higher retention rates; in plain English, that means that a company who shows their employees a path upwards will tend to keep their people.
To speak in sweeping generalizations, most managers are motivated by money, stability, glory, or altruism. Fleet manager training feeds each and every one of those motivations. Knowledge opens up a few more rungs on the corporate ladder, meaning those motivated by money and glory can chase both. It teaches your team to do things "the right way," which rings the stability and altruism bells. And learning best practices can help introduce new ideas to the company, so even those rebellious managers can feel like they're making an impact.
Reason No. 3: Fresh Ideas
Inject new ideas into your company. Promoting from within has a ton of advantages: the person is known by their subordinates, it improves morale by showing other employees that hard work is rewarded, the ramp-up time is often lower. One potential problem with hiring from within? Very few new ideas get implemented. Training and education means exposing them to new ideas.
Reason No. 2: Big Picture Thinkers
Cross-trained managers negotiate to get the best outcome — rather than their favored outcome — in mind. This comes into play when there's inevitably a shortage of budget or manpower or both. When something's got to give and managers have to hash out where to cut without hurting the business, you want managers who defend their turf but also understand their co-workers needs. And to be blunt, it helps to be able to speak the other sides' language. Plus, if you're the safety guy who understands maintenance, it's a little more difficult for the maintenance guy to BS you.