Typically major revisions (7.1 to 7.2, 7.2 to 7.3, etc) have a beta period; typically minor revisions (7.1 to 7.1.1, etc) are minor bug reports and don't require a beta period.
Typically the testing period of a beta is as follows:
1. Received by the Private Beta Group and tested for several weeks until bugs can be ironed out.
2. Pushed here at UBBCentral for user testing for several weeks until any bugs can be ironed out (typically a week or so with no bugs will be classified as successful).
3. Provided that no bugs have been located, the public will either see a public beta if items need to be tested, or will recieve the tested revision as a final.