Reading these posts about people hammering the update servers for apparently no good reason (posting about being "stuck" on defs update from Oct 27 on Oct 28 03:01:18, oh noes!), I'd hazard to say it'd be beneficial to eliminate the defs versions from the GUI altogether. They make very little sense with the streaming updates anyway.
Your avast defs are getting updates many times every hour, people! Just browse to the defs folder to see for yourself. Just chill and stop babysitting the thing when there's no need!