“Generally will not release builds on weekends” (Gabriel Aul).
But it seems like Gabriel Aul is a big fan of exceptions. Today for example Microsoft releases the new Windows 10 build 10565 to the fast ring.
Microsoft added some new features to the new build. Microsoft Edge has now a Tab Preview and it can sync favorites and reading list items. Furthermore you can now try the new Skype messaging, calling and video experience.
They have also worked on the design of Windows 10, the context menus on Start have been adjust and improved and the context menus are including new icons for tile adjustments and there are more vibrant title bars now.
Microsoft has fixed some problems of previous builds for example the automatically app update should work now. Nevertheless there are also some issues in the build. If you are in a country where Cortana is not available the search box does not work.
You can find more information here.