why is it that surgery takes months for professional sports athletes?

You're probably think about the aftermath. What they do could aggravate the injury if they return too soon. Like a quadricep injury for example usually requires around 7-8 months of rehabilitation.

If they tear their ACL that could take multiple surgeries and months of rehab to get the player back to peak performance. And even then they have to be wary of not hurting the area again.

Their thingamajigs need time to heal

The surgery takes hours at mosts

I imagine it depends on the surgery. Chances are it’s fixing something severely injured.

You mean recovery?