Hi Bankable
It used to be that whenever I touched a page there would be a fall. I'd messed with it and Google didn't like it! Now I find that any changes that add value rise in Google and quite quickly too! Pages that I edit are picked up very quickly, literally as often as Google passes by and re-indexes a page. You can get an idea of how frequently that is for these pages by searching for them then clicking on the green arrow right of the URL to see when they were last cached (See Image). Could be up to 4 weeks, but I find that the higher the page is up the hierarchy, the more frequently it gets crawled.
When you say Domains I think you mean URLs?
For on page content I would recommend you stick to 300 words+ and make sure that the content you are adding is focused around a single keyword or a small group of contextually similar keywords and short phrases. Don't splurge content between different pages - make sure the writing is focused.
I see little difference in changing 10 pages in one day or 10 pages over 10 days so go ahead and if you can improve on what's there quickly then do it.
Regards Nigel