Exactly. If you hand me a presentation and hopefully some notes associated with it and tell me that I need to fill in, I can do it but I'm going to need to spend some time (and will probably rearrange things a bit).

But if you tell me give some variation on your talk about $X, I can probably be ready in about 30 minutes. (And, in fact, I've dropped in a conference presentation in response to a 3am email because another speaker forgot they were supposed to be there.)