A great coach does not need to know it all.
How could one person be an expert in everything.
In football, can one person really be the go to guy in offense, defense, special teams, kicking, blocking, tacking, nutrition, strength and conditioning, motivation, offensive line, defensive line, keeping parents happy, making sure their kids stay academically qualified, keeping the AD informed, equipment, hydration, practice scehdules, recruiting talent from within the school, and all the little things that make bigger things happen.
In track and field if your team is not that strong in sprints, well find a good sprints coach. The same goes for a program who lacks distance, throwing, hurdles, or jumping.
Not one person can do it all. That is why a great coach surrounds himself with great assistant coaches.
If a CPS team wants to build up their program finding, attracting, and keeping the right assistant coaches is one of the keys.
Or if your program cannot or does not want to get or pay for Assistants, then you better educate yourself or surround yourself with advisors that compensate for your weaknesses.