It means that everyone has a reason for doing something for their own private reason.
We all do things for our own reasons, not for those that might seem obvious to others.
every officers on the team does. the officers have their own meeting before every meeting to prepare the agenda and what will be going on at that meeting with the aid of the advisor(s).
"Every man his his own agenda," is a metaphore, meaning everyone his their own problems, so you shouldn't expect them to be thinking about yours, just like you aren't thinking of theirs. If someone speeds on the road, or pushes past you at the store, you may think they're just rude, but they're just worrying about themselves. This may sound selfish, but what were you thinking of when it happened? About you, not them. Everyone has their own agenda and minds it, not yours.
It means that everyone has their own way of doing things. They have their own motives and they do things for a reason.
Grenades
Every franchise owner has their own business license. If they own more than one McDonalds, they only have one business license.
Grapevine communication is the informal network within every organization. It is characterized by lack of managerial control, trusted by employees, and it can be used to promote ones own agenda.
every thing in it's own time
after my own heart
After elections, senators then elect their own officers to run the agenda and processes. They elect the leader and the whips.
You move on and forget about it, he may have his own agenda and would prefer to do the asking.
one's own country