Starting March 3, Windows Insiders will get firmware updates automatically
Firmware Auto-publishing for Windows Insiders
Microsoft has announced that starting today (March 3rd), anyone enrolled in the Insider program can receive new firmware updates automatically, without rolling back to Windows Phone 8.1 or changing the Insider Ring to Production.
From today, the Insiders will receive device specific firmware updates automatically, regardless of the Insider ring, as long as the firmware update is available for that device.
Keep in mind that firmware for carrier devices (locked) still require an approval by the carrier to be unleashed.
Microsoft has also mentioned that some of the old Windows Phone 8.1 devices will be getting new firmware updates before the official update to Windows 10 Mobile in order to fix some device specific issues.