Bugzilla

For example, 67 released recently with the pinning expiration time set to Aug 15 2019. Since we're planning on releasing 68 on/around Jul 9 2019 (according to https://wiki.mozilla.org/Release_Management/Calendar anyway), those pins will still be active for about a month in 67 at that point. (So it looks like n+2 isn't really true any longer...)
In any case, when those pins expire, they won't be enforced, so expiry would make it easier to update rather than harder.
Some quick back-of-the-envelop calculations using https://mzl.la/2KqkNvl and buckets 32/33 (failures/successes for *.cdn.mozilla.net) indicate 160k failures vs 707m successes, or a failure rate of 0.02%. (I think I can run the numbers on release using atmo if necessary, but it might take a little while.)

For example, 67 released recently with the pinning expiration time set to Aug 15 2019. Since we're planning on releasing 68 on/around Jul 9 2019 (according to https://wiki.mozilla.org/Release_Management/Calendar anyway), those pins will still be active for about a month in 67 at that point. (So it looks like n+2 isn't really true any longer...)
In any case, when those pins expire, they won't be enforced, so expiry would make it easier to update rather than harder.
Some quick back-of-the-envelope calculations using https://mzl.la/2KqkNvl and buckets 32/33 (failures/successes for *.cdn.mozilla.net) indicate 160k failures vs 707m successes, or a failure rate of 0.02%. (I think I can run the numbers on release using atmo if necessary, but it might take a little while.)