Which is why some of us actually align the cantilever as best as possible using accurate set-up gauges.
I thought this was interesting when searching for better tools to align and adjust overhang of my cartridge. Maybe someone has mentioned this before in another thread, but it looks very intriguing and could be the answer to setting a cartridge extremely close to ideal settings. It's called the Mint best Tractor: http://www.mintlp.com/best.htm . Also here is a discussion about it at the audiogon analog forum: http://www.audiogon.com/cgi-bin/fr.pl?eanlg&1219353750 . I have sent an email about obtaining one for my setup since there could be some discrepancy with how my cart is aligned. This seems worth trying out especially since it addresses overhang and null points. Some have commented that it was better and more accurate than the Wally tractor's they had. Anyway, thought it might be interesting....