Today is the second Tuesday of February, and that means it should be Microsoft's Patch Tuesday. It should be a big Patch Tuesday, too. First, there's an in-the-wild zero-day flaw in SMB, Microsoft's file sharing protocol, that at the very least allows systems to be crashed, and the patch should be released today.

Second, Microsoft is continuing to tune the way updates are delivered to Windows 7, 8.1, Server 2008 R2, Server 2012, and Server 2012 R2. The company started moving to a Windows 10-like cumulative model last year in a bid to ensure that the configurations the company tested (all patches applied, all the time) matched the end-user experience. Each operating system is getting two packages a month: a "Monthly Rollup" and a "Security Only" update.

The "Monthly Rollup" contains both security fixes and general reliability improvements, and it's a cumulative update, incorporating both the current month's fixes and historic updates. The intent is to make it easier to get a freshly installed system up to date; instead of installing hundreds of individual fixes, the latest Monthly Rollup should do the job.

The "Security Only" package isn't cumulative, and it skips the general reliability improvements.

Starting this month, the Security Only package is changing a little. Previously, it contained both operating system and Internet Explorer fixes. Going forward, however, the Security Only package will only contain non-Internet Explorer fixes. A second package, the Cumulative Security Update for Internet Explorer, will apply browser fixes. Like the Monthly Rollup—and unlike the Security Only patch—the Internet Explorer package will be cumulative, containing both new and historic patches. Microsoft says this change is being made to reduce the size of the Security Only package.

The deployment system is also being refined to ensure that neither the Security Only patch nor the Internet Explorer patch will be installed on machines that have a current Monthly Rollup.

This is all well and good, except it's not happening. Due to a "last-minute issue," Microsoft has delayed this month's updates, and currently, there's no expected time of arrival. This delay may hint at one of the downsides of the combined patching: in the past, an individual fix might be held back due to a late-breaking problem, but other fixes could still be delivered on time as expected. With everything bundled—and, critically, tested—together, the company may be more reluctant to punt an individual fix to next month.

Still, if the delay means that Microsoft is avoiding shipping a fix that breaks people's computers, it's probably for the best.