What's your update rule-of-thumb?

Do you update every new edition?
Only when the revision seems relevant to your usage?
Only when it's a full number?
And how do you decide? :blink:

I'm probably THE charter member of 'tech illiterati' so please bear with me.

Does each download completely overwrite the existing data or does it just update?

I have wireless, but I'm right on the edge of the hinterlands so service is lousy, downloading is slow and anything over 3 Mb, I usually wait until I can get to a hotspot - or I end up with small corruptions and large frustration.

THANKS!