for a number of years it was 6 to 7 months apart. The only time they have lapsed in that was during the changeover and relocation of Alias.
I'm not saying thats a good timeframe, but thats why small things are rolled out each version. I can't see 7 comming out in the Fall unless they have been really working on it for a while and rolled out only part of the improvments in 6.5
Overall, 6.5 seems a lot faster and stable compared to 6 release. So I'm happy with it.