This has also been a problem for me and most of the time I have UseExtrusions set to off… I have argued in the past for this to be set to off by default, but there is also strong argument for having it on - notably the one-way conversion from extrusions to polysurfaces much like going from NURBS to meshes. If you make a couple of thousand extrusions, it’s easy to convert them all to normal surfaces/polysurfaces with a couple of clicks, but if you start out with polysurfaces, and you want extrusions to conserve file size, you can’t go back the other way.
–Mitch