The mid afternoon release, it became available just after 3 PM Eastern, was out of cycle for the normal early afternoon (1 PM Eastern) or the early evening (6 PM Eastern) releases we normally see from Microsoft for Insider builds.
Friday's build releases are the 16th development branch builds for each platform (PC/Mobile) and begins the Fall Creators Update stabilization work that Microsoft discussed earlier in the week when they released Build 16273 for PCs.
As expected, there are no new features in either of these builds but there 7 and 9 changes, improvements, and fixes listed for PC and Mobile respectively.
This was the second PC build in as many days with the release of 16273 just two days earlier but it had been more than two weeks since the last mobile build, 15240, was made available.
We also learned the day after Windows 10 Mobile Build 15245 was released that its predecessor, 15240, was pushed to Windows Insiders on the Slow Ring to broaden the testing surface for that build across mobile devices.
This was the first time Microsoft did not release a build in the Redstone 4 Skip Aheadbranch that is the pre_release channel for the Spring 2018 feature update that will begin testing in earnest as the Fall Creators Update development ends. This diverging of branches should result in Microsoft incrementing the RS4 channel to a new base build number as they begin adding new code to that branch. Initially it looked like that base build number would be 17000 however, there might be an issue with that being used in this next branch.
Note: Skip Ahead is full so if you are in that branch and opt to go grab the latest RS3 builds you will not get your spot back in Skip Ahead. That means having to wait for new RS4 testing builds until after the close out work on the Fall Creators Update.
I guess we will see soon enough what direction Microsoft takes with the build numbers for RS4 and just how often these faster builds for RS3 will be arriving. Expectations are high for 2-3 builds per week as we are likely in the final few weeks of work on the initial public release of the Fall Creators Update.
I will be sticking with my prediction that the final Fall Creators Update build will be in between build 16290 and 16300.
What do you think?