And there is always the problem that any movement relative to the lead requires 3 control inputs.
Say we are wide and wish to move closser to the lead.
A little aileron, the heading changes and sure enough we start to move in.
Now to stop the movement we must change the heading to parrallel the lead. But our aircraft now has linear momentum inwards relative to the lead, so it is neccessary to overcompensate, or to change the heading so it is actually away from the lead.
When we are now stabalised we can only now change heading to match the leads.
Works in all 3 planes but most obvious in fore-aft with the power. Most critical is lateral.
Oh and when you are moving in, you are travelling further, so need power, which once again will require 3 movements. every movement relative to the lead will require a power change as well as control input.
Most important thing in formation is the lead, if they do not do the job well, form is nearly impossible.