What exactly do you want to accomplish?
About a year ago, the criteria for changing the last_update date on topics has changed. While edits on the last post no longer bump it to the top of /latest, edits on the first post of topics in a category using the doc-categories feature are bumped. In those categories, a bump can be caused by a reply or an edit on the first post now. So it doesn’t necessarily mean there was an edit, but it helps noticing edits on a post where changes are important.