Didn't beta 4 on the 3.0 series also break the bi monthly release?
Found this online for 3.0:
* Beta 1 (7A238J) was released on 13 March
* Beta 2 (7A259G) was released on 31 March (18 days later)
* Beta 3 (7A280F) was released on 14 April (14 days later)
* Beta 4 (7A300G) was released on 28 April (14 days later)
* Beta 5 (7A312G) was released on 06 May (8 days later)
* 3.0 GM (7A341) was released on 08 June (33 days later)