How do I know? I am one of the over 3.5 millions of US citizens who live in a rural area and/or have no option but to connect to the internet via dial-up service. That means that I manually do a Live Update every day.
Last month, there was another 150 MB Live Update. It took 40 hours to download. No, that's not a typo; it took 10 hours each time and the first 3 downloads crashed at the very end.
Thus far, three Norton support staff have told me that if I "want" to use dial-up, I should use another anti-virus program. "WANT" to use dial-up? (Me, off the phone, screaming at a pitch that is driving the neighborhood dogs crazy: Who on God's earth would WANT to use dial-up?) Besides, that's not the issue. I've used NIS since 2000 and pay the same subscription rate as everyone else. I shouldn't have to do the equivalent of a week's worth of work to download one day's worth of definitions just because I don't have access to a high speed connection!
A more reasonable solution would be to set a maximum packet size for anti-virus definitions that is effective for all users. It is difficult to imagine that, after weeks worth of 10 MB or less Live Updates each day, there is suddenly a need to dispatch 150 MB worth on one day. But even if there was, reducing packet sizes would help. If there there had been five 30 MB downloads today, I could have gotten at least half of the protection today and phased in the rest tomorrow. As it is, I'll have to wait for a full 10 hour stretch of good weather (e.g. sans thunder and lightening storms) when I can forsake my usual access to the web and devote the full resources of my internet connection to downloading a ridiculously large Live Update, which defeats the purpose of your lauded immediate protection.
Surely, you have the technological expertise to make this simple change. How about a little slice of compassion for those of us on dial-up to go with it?