HTTP Live Broadcast Less Than 10 Seconds?

Question

We are trying to make low-latency video on iOS, following Apple HLS rules for video over the cellular network. From a technical point of view, we can set EXT-X-TARGETDURATION: up to N seconds, where N is less than 10 (I think 2 or 3 seconds).

In practice, is this allowed? Does anyone encounter application validation when using HLS segments of 5 seconds or less? I heard anecdotal evidence that this is forbidden.

Regarding Apple rules, nothing I've seen has a minimum segment limit. However, there is a technical note that states:

"We highly recommend a goal duration of 10 seconds."

The question is whether this recommendation is actually an undefined rule.

Source: http://developer.apple.com/library/ios/#technotes/tn2224/_index.html

One more note. Apple provides a "Media Stream Checker" that does not report errors in streams with a duration of 2 or 3 seconds. This once again suggests that the duration of the stream is "valid".

Thanks for any experience / thoughts. Also, if you know of any approved apps that you think use HLS segments of 5 seconds or less, this would also be useful, as I can check if they really use a shorter duration and use it as comp for Apple approval.