I'm aware that editing tags en masse is not encouraged. But going back and editing older questions to update the tags seems to be OK. When a new tag is created, what is the current/best practice? Go through old questions which fit the description of the new tag and edit that tag in? Or apply the new tag solely to new questions?
If I/someone who interested in tag comprehensiveness were to edit the older questions, would those edits be beneficial? Frowned upon? Inconsequential? In other words, is a tag intended as a complete compendium of all questions which fit its description?
I'm interested in what people think should happen as well as (generally speaking) what actually does happen.