Added influence and relationship gain is useless. You don't need relationship to recruit vassals the best way is take every fief of a kingdom then recruit vassals.Very
You can always stay in just one war. Thou art the king and influence is the currency of kings.
Influence is also the currency of numbers and speed. You can choose to use an exploit to get it; but if you dont, every source is valuable.
No money is king for staying in just one war.
Money is the currency of numbers and speed. Influence is only needed if your going to take down a faction from the inside. Outside of that influence is worthless.