About AMP Release Streams
AMP has 4 different release streams to allow users to be flexible about when they want to try out new AMP features and versions.
MainLine releases are the formal, stable releases of AMP that get publicly announced. They're expected to be stable and not to have any serious regressions from previous versions. MainLine releases are typically 1 or 2 times per month at this time. These releases go through manual testing and validation to ensure that all of the core functionality is working correctly.
FastTrack releases are weekly, they're a roll-up of the most recent weeks changes and generally receive some manual testing, but this is not as extensive. Users who want to try out new features a couple of weeks before they're widely available may want to try out FastTrack.
These builds are produced at 3AM every night. They receive no manual testing and only go through the automated test suites. These builds may randomly break and are generally not suitable for use except to try out specific new features or fixes.
These builds are produced immediately as soon as a code checkin is made, and several may be built on a given day. Only users with a Patreon, Network Premium or Enterprise licence are able to use these builds. As with Nightly they only undergo automated testing and are liable to randomly break or stop working.