How to people feel on the use of rhetorical questions in narrative? For example: Of course, Simon noted this. How could he not? I'd imagine that more than one rhetorical questions in a paragraph would be a bit much, no?
They're perfectly acceptable. Not necessarily. It all depends on whether they're needed or not. Only you, as the writer, can be the judge of that.
If used appropriately and sparingly, it could be a great device. I actually love rhetorical questions so much I overuse it. I'd limit it to one or two per page, as it gets annoying quickly and if done wrong, it could come across as either 1. author's being patronising or 2. said character is a little slow/dumb. There's also personal preference at play - some readers prefer to work things out for themselves and rhetorical questions can serve to spell things out sometimes, or else to force the reader to ask certain questions that they don't feel is necessary. But others would feel it adds to the character's voice and makes the character more human. Basically, in short, use it, it's a perfectly good device. But make sure you use it well - stupid or obvious questions may annoy the reader rather than improve the reading experience.
