I can't believe they're up to 40. I remember installing Fedora Core 1 like it was yesterday. Yum (and now dnf) has come a long way. It used to have to individually retrieve metadata files for every available package, rather than using a single compressed index of all the packages available in the repository you were using. It made just getting to the stage where dependencies were calculated take forever.
1 every 6 months or so. so 2 per year. The main difference with other distros is that Fedora is always improving and adding new tech developed in various projects that make part of the FOSS world.