Here is an interesting reply on Quora:
The answer seems like common sense. "Short" and "long", "tease" and "bore"
- Don't send a "short" 3 page slide deck crammed with font size 8 text
- Don't send a 3 page deck that is so vague and mysterious that the VC does not understand what it is about ("do you want to share our journey that will revolutionise personal finance?")
- Don't send a super looooong slide deck does not get to the point even on slide 15 because you are still setting the market context and ticking of the hottest buzzwords
- Don't send a long slide deck full of (confidential) details about your finances, product pipeline and roadmap, competitive strengths and weaknesses and the last Board decisions
"Short" and "long", "tease" and "bore", the smart approach sits somewhere in the middle. VCs are usually reasonably intelligent, and have likely seen many, many pitches from companies that operate in the same field as you do.
You could almost compare this to you checking out a web site of a new competitor to your business in your industry. After a few seconds, you either utter a sigh of relief, or get that feeling, "hmm, this could actually be pretty good". The VC will look at your deck in pretty much the same way.