In November, Microsoft pushed out build 9879 to Windows Insiders and said they were going on a break over the Christmas holidays. Of course, internally Microsoft continued compiling builds of Windows 10 up until mid December, so the real reason why Microsoft stopped issuing Windows Insiders new builds is so the company could surprise the public at it's recent January 21st event.
The wait between 9879 and 9926 was a little over two months, and as a Windows Insider, those two months were dreadful. Luckily, Microsoft's Gabe Aul promises that there won't be another pause like that anytime soon, and that the time between builds being pushed will be faster as time goes on. This means Windows Insiders will have new bits to play with more frequently, which means more feedback for Microsoft to collect.
— Gabriel Aul (@GabeAul) January 25, 2015
So for those Windows Insiders who are already bored of build 9926 and have given all the feedback possible, you may not have along wait before the next Windows 10 build is available to you. Build 9926 was the last build compiled before the milestone 10000 build, so we assume the next build to be pushed will be in the 100xx range.