Firefox and Chrome both have the same update cycle - a new major version every 6 weeks. I believe the main reason for both projects doing it are allowing them

Firefox and Chrome both have the same update cycle - a new major version every 6 weeks. I believe the main reason for both projects doing it are allowing them to get improvements and new features to users faster. One or two releases a year means a very long time before improvements get to users, and it holds everything back. 6-week releases means you get improvements to users in just a few months. Of course there are downsides to 6-week releases. If you prefer a slower-updating browser, there are other good options, such as Opera. And if you want even more stability, there are Safari and IE, which these days are quite good as well.