I was hoping to get some insight on how people have handled leadership roles in their campaigns... Obviously it's still a party-related thing, but have most groups allowed the ruler to have actual, absolute decision making on all regards (like an actual leader of a kingdom would), or have you done more delegation?
I think you should examine your core assumption here.
Actual historical examples of monarchs would inform you that they delegate, and are often beholden to, their advisers quite a lot.
Philip the II (Alexander the Great's father) had to engage in a lot of machinations in order to ensure he himself was king. After his death, Alexander had to do a lot of maneuvering and fighting in order to be recognized as undisputed king.
In addition, as Alexander conquered, he often utilized the previous administration to rule for him. He'd kill the enemy king, then just leave everything else as it was. He often installed a couple of his officers as his representative, but then below that officer would be the advisers and court officials who were there before Alexander took over.
If a king orders your execution, but the executioner just sits there... does the king's order matter? If the king draws his sword to kill you, and the executioner comes to your defense... is the king really in charge?
If you need more historical examples, I can provide them. All the way from Augustus to Stalin, every powerful ruler was backed by a lot of people who had a vested interest in maintaining the ruler's power. A few were ideological fanatics, but many found it advantageous to their own ends as well.
If a king is enriching himself at the expense of those who he needs to hold onto his kingdom... that's a recipe for being assassinated.