the size of the Lagrange points
varies, they are only the midpoints of zones where the gravitational forces add up the most. An object placed there will tend to oscillate around those points over a wide area. Think of it as dips or wrinkles in the gravitational field, objects placed there do linger, but will drift in and out as they are affected by gravitational tugs from passing objects But the tendency is for them to go back eventually.
https://en.wikipedia.org/wiki/Jupiter_trojan
The earth's Lagrangians