MAME release schedule:
Sunday before the last Wednesday of the month - freeze applied, release branch created.
The next Wednesday - MAME released (built from the release branch), then that branch deleted.
Meanwhile, developers can continue working, but those changes will appear in MAME a month later.
Recently MAME has not been released when advertised, due to real life matters affecting the release scheduler, mostly due to the effects of the Chinese virus. After see