Movable pulleys can move axes, unlike fixed pulleys.
Movable pulleys have the advantage of being able to move with less force.
But, the distance that I have to move is longer than fixed pulley.
So, there is no benefit of energy.
Movable pulley is used with fixed pulley because it is difficult to move by itself.
Movable pulley with 1-wire
Each time a Movable pulley is added, the length of the pulling line becomes longer. Instead, the force required to move the object is reduced.
The size of work is the product of force and workout distance, so the total amount of work is the same.
The unfolded pulley is inconvenient to use. Actually, we use the pulleys of the combined shape.
In the figure below, there are three lower movable pulleys, so you can lift objects with 1/6 force.