- App store update notices are not "pushed" to your Mac like a message, instead your Mac checks for updates once a day. So it is entirely possible an update may appear in the app store just after your Mac checks resulting in at least a 24 hour delay before you know about it through the App Store.
- There two versions of many (most?) apps in the App Store, one for direct release from the developer which may or may not fully conform to Apple's standards and one for App Store release that does conform with Apple's licensing, version checking, and operating standards.
- Because Apple insists on vetting updates before making them available in the App Store (and sometimes rejecting updates for a variety of reasons) there can be a delay of days or weeks between the release of the non-App Store and App Store versions.
- The update notices that appear on MacUpdate and other sites may not be the App Store version.
- Those sites rely on the developers to notify them of an update and the developer may jump the gun assuming Apple acceptance, and you know what happens when you assume.
If we knew what it was we were doing, it wouldn't be called research, would it?
— Albert Einstein
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