I have certainly seen plenty of applications that don't have a timestamp in every row of every table.

Oh, I know, and I've seen them as well. The best practice is every table. See my last message to William. You never know when it may come in handy.

I had a knockdown dragout argument with a DBA about implementing triggers to always post a lastupdate and lastupdated user - normally a DBA is the first to want that type of protection.