Let's fight over fictional characters

"Traditional" spider mans web fluid is a cross link polymer related to nylon. Esthers in the fluid break down after a few hours (plus or minus by special formulation as desired) and cause the web to dissolve into a fine powder. The Spider-Man with biological webs likely shoots webs more like a real spider. These webs would be composed of protein chains which in theory could be quite long lived. Studies show enzymatic decay in webs can take years. Of course the proteins can be harvested for nutrition by scavengers, and environmental effects can break up and damage webs or speed decay. I am unaware if there is an explaination given for biological web Spider-Man. Ignoring the symbiot webs since the symbiot could easily make webs to degrade or not as desired.

this has actually been gone over in the comics... they do disintegrate. Spider-Man isn't a jackass.