HTML generation is currently a pain, esp. as display can't be locked
or it won't work - and it is easy to break generation of a couple of
pages because of the infamous "X Error of failed request" already
reported.  Allowing to ask refreshing of failed pages only would be
great.

Additionally, when working on a presentation, I usually work of a
small range of pages (usually the last ones in the slide), and make
the whole HTML available for real-time peer review.  And later
correcting typos do not require refreshing the whole.  Thus refreshing a
range of pages would even be interesting after Bug #51544 is fixed.