Nice topic here.
I would not hesitate to put 2000/year through a gun in reasonable condition. Two thousand is a ton of hunting, but not much at all at the traps, and I would expect that most of our guns will have to survive some time at the traps in order to get to the field.
There are a lot of variables. I think it was in an article about Fabbri where it was stated that the two most important aspects of a good shotgun are metallurgy and fit; design was in there, but down the list. As mentioned before, cleanliness and lubrication are biggies (I am trying to recall encountering a worn out gun that had visible lube). Then there's the outlier, like my early-manufacture Ruger Red Label with about 75K through it, no repairs and no malfunctions, though I did have it rebolted recently.