I wrote an article on my blog, where I explain the relevant factors, when it comes to the question "how often should I call session.save()?". The rule of thumb was always "do a save after 1000 nodes", but this might be already too high. Check this article and learn how you can estimate the size on your own:
Thanks for sharing such a nice information with the community.
Let’s conclude: The rule of thumb “do a save every 1000 nodes” might be a bit too optimistic on AEM 6.2 and older (with default values), but ok on AEM 6.3. But always keep the amount of transient space in mind. It can overflow your heap and to debug out-of-memory situations is not nice.
Sums up very nicely.