At one point, I read that the rule in question, is you cannot push new features without going through the approval process again. So it really comes down to what Apple considers "new features". People have definitely pushed bug fixes, and even small features, without issue.

Perhaps ironically, when I worked on the iTunes Store (which is mostly all HTML and JavaScript) there was hardly a week went by that new code didn't get pushed (mostly bug fixes and under-the-hood updates). Yet Apple only really announced new iTunes Store features several times a year. So, one would hope they understand the need for continuously updating a complex piece of software, versus shipping major pieces of new functionality.