Do you study the act who follows a bomb, or the act who follows a killer set?

I keep thinking those are two completely different bits of stagecraft. Following a rough set means the room may need settling; following someone who smashed means you can start comparing yourself before you've said a word. If you're watching stand-up to learn rather than just enjoy it, which transition teaches you more? I'm especially interested in what you watch in the first thirty seconds — pace, first line, whether they acknowledge the previous act, or whether they just get on with their own thing.