In a post to a company blog, Mozilla said it would use a variable release tempo in 2016 with six-to-eight-week intervals.
Chrome has used a flexible schedule since its September 2008 debut, shipping a new edition approximately every six to eight weeks, but unlike Mozilla, has never set delivery dates ahead of releases appearing.
"Four years ago Mozilla moved to a fixed-schedule release model, otherwise known as the 'Train Model,' in which we released Firefox every six weeks to get features and updates to users faster and move at the speed of the Web," Mozilla said. "We studied the process carefully and learned a lot. We have also identified additional areas for improvement and it's time we iterate again."
Firefox shifted to a faster release tempo in 2011 and has discussed changing the intervals before. In September 2011, it considered -- but rejected -- a move to an every-five-weeks release schedule.
Mozilla cited several reasons for the schedule tweak, including a nebulous "We will now be able to adjust release dates to respond to emerging user and market needs," and that the new cadence will account for holidays.
In the past, the open-source developer has departed from six-week intervals around extended holidays, especially Christmas and New Year's Day.
Mozilla said it would deliver the same number of releases during the year as it would have under a six-week schedule, but according to its calendar, the number of editions will actually drop from nine in 2015 to seven in 2016.
In December, Mozilla plans to follow Firefox 50 -- which has a Nov. 8 launch date -- with Firefox 50.0.1 after a five-week gap, but only if necessary to deliver critical security fixes. Mozilla usually times its security updates with a regularly scheduled release.
Firefox 47, currently set to ship on June 7, will be the first outside the previously inflexible six-week timetable. The current edition of Mozilla's browser is Firefox 44, which launched Jan. 26.
Mozilla publishes Firefox's release schedule on its website.