It certainly is adjustable - and something that certainly can be looked at to address.
The 5-part post was certainly an exception to general usuage! Do you really think you'll break that limit more often?
The trouble with raising it too high is that perhaps it is better to break a
very long post into smaller parts, for easier readability?
Still, there is no real harm in doing so, I suppose.
I'll see what others suggest, and see if there's a general agreement on what should constitute a proper and sensible limit - if one is even necessary.