If MacUpdate (which I never consult) is generally far behind the times, why is anybody using it, especially those who ultimately revert to the original distributor to acquire the update?
I have a handful of applications which regularly or frequently update their versions (eg, MS Office for Mac 2011, Shockwave Flash, Java Runtime, Firefox, Thunderbird), and it only takes a few moments to check them all directly — which I may do every week or so. (I check Firefox's Add-ons more frequently while I'm using the browser, which adds no time or inconvenience at all.) If there is any update, it then just takes a single click to download it.
That seems to be a far more efficient method of getting updates. So why take a "detour"?
Good points, grelber. There are some instances where listed updates are very, very current, and thus it provides a "lazy" way to seeing which updates are available. But, even if all of them were current (my example above shows why that is not true), the idea of having to use their "forced" installer is just plain unacceptable.
As for checking each application for updates, some of them (like 1Password) inform users of updates right away, even without launching the application. Others will let you know of an update when you launch the program (such was the case for me for Onyx which I launched on Saturday to start my weekly disk cleanup/maintenance/repair, and backup, processing. It let me know that a new version was available (EtreCheck does the same). Yet, MacUpdate did not show that newer version of Onyx until today). Then, of course, when one starts the app, a number of them have a "Check for Updates" option. And then finally, one can do a search on their own.
In summary, you are correct. I guess it's kind of force of habit for me.