Yeah the engine used to have a limit for each item type. I once tried to make a necklace for shaolin (in '09) as a helm and parts of it kept disappearing randomly while the engine was drawing it. I think it became stable around 400 polys. The engine has probably been upgraded but you always want to use the fewest possible polys to create your items, especially if it's for retail or a popular server to keep the overall performance at the best place you can. Typically my weps are under 200 each (some as low as 50), my armors and chars are under 1.5k for C3's. My effects are mostly done with particles and planes so it doesn't work the same way with those.