Yes, that seems like the norm....a customer of mine said he went through three factory transmissions in his SSC before giving up and going to a different car (Brent something, look him up).
We are running Royal Purple Max Gear 75w-90 GL-5 gearbox oil in a friend's '05 Mazda3 that is an autocross car, and the shifting has improved over the stock fluid (albeit 45K miles old), seemed to have liked it after about 10K miles of driving and autocrossing.
AMSOIL also makes a Severe Gear 75w-90 and 75w-110 that would be great for racing, works well in the Subaru (notoriously fragile), and I am not easy on it (200K miles and lots of ProSolo launches, original tranny).
Keep in mind also that the current spec of 75w-90 as of 2008 is on the "thinner" range of the previous specification, hence the "new" 75w-110 spec coming out to meet the needs of pre-'08 cars that originally spec a 75w-90...unless you don't race and/or drive where it is cold enough to warrant a thinner gearbox oil, the 75w-110 might be the way to go.
EDIT-- Link to info for the spec change: http://www.lubrizol.com/products/automotive-gear-oil/J306.asp
*Banned Again* Permanently