When should we edit old questions?

Question

During the discussion of this question, two users suggested that editing older posts is harmful. Since that question really has nothing to do with editing old questions (it was suggesting that people include alt-text going forward; although, this answer does suggest editing previous questions), I'm making a new question to deal with the larger issue.

It's interesting to see how people use the site differently. I only play a couple of games on the site, so I never go to the front page. I first came to the site through a question page and came back through that page. More recently I switched to the Diablo 3 tag page, as that's the game that I'm playing now. It sounds like other people use the site differently. Do we have any stats on whether most users are like me (never visiting the home page) or like those who enter the site through the home page?

Some related (but different) questions:

• Why does editing a question or an answer resurrect it?
• Should we go through old questions of newly released games and update them?
• Whats with the recent spurt of chain editing?

When is editing good and bad? Does question age matter? Does it hurt the site for some questions to get bumped (because either the question or an answer was edited)? What do you think?

Answer 1

Editing old questions to improve them is never bad.

Editing large quantities of old questions in a short period of time is bad, in that it renders the main page relatively useless.

In this situation, it seems like it calls for doing a couple of edits an hour, or editing when you see a problem, but not searching for one. This will keep the main page useful while improving the site's content.