Furlongs, treat this as hearsay, and I don't think you'll like this idea any more than the ones above, but since all you want is an answer to the question you asked, here goes -

I've heard some places that you should create a page once, with the correct URI the, the correct content and everything and just leave it there. Change as little as possible and don't change anything as far as possible.

I don't take much heed of it as these are short term ranking fluctuations and I don't change a page till I know this time its for good. Maybe once a year or so when I do this, it usually totally a different page as far as SE's are concerned, so its fair to rerank it, its something I account for.

I have seen my pages change positions when changes are made to the content. Usually return to a better position, but they do even disappear for short periods, sometimes even a month or two. Might differ depending on the trust level of the page/site - IMO.

I've always taken it to be the way things work with SE's, and they should, a changed page is a different page that might be ranked differently, either better or worse.

So IMHO, dump the regular updates to pages, start making long term overhauls to the website or sections of the site instead. You already know where to start with that.