The reason for this is twofold:
* Running the release at the same time as the build means we are likely to miss the actual XPI file we need to build. This is a race condition introduced by this being a different workflow that waiting a bit should at least paper over.
* While our policy was "release on Fridays", this was Friday in US time. Workflows are scheduled in UTC, so it was coinciding with the Thursday nightly.
TÖRÖK Attila