Comment 15 for bug 1766542

I don't think we can realistically go lower than 2x30s - I think the intention is to add the mirror and security separately and comment them out if they don't work or something, so they need to be in seperate apt runs. Unless, of course, we write a tool in python or something that does update there and inspects failures and checks which hosts errored out; then we can do it in one.