assitance excercises

Apologies if these are commonly answered questions... What assistance work is recommended? Is it even necessary? How much pushing / squatting should you do to off set the pulls / hinging of the DL and pull up? Would presses/dips and front squats be good? Would weighted pull ups be a good...

I know it is different within a week, but do all your main exercises follow the same intensity and volume dynamic for the month? Also, within a week, do you use a separate intensity dynamic for assistance exercises or the same dynamic as the exercise it is assisting for? Thanks