I agree the spider-caffeine-thing is "weak". But it's a popular argument and I don't have anything more substantial at hand. Most people I know, that still drink coffee/caffeine do tell tales of feeling "wired" and "scattered" after consumption.
From persona experience i either have to go a few days without or drink my third cup (drip brewed) of the day to get anything noticeable.
No jitters but if I take all 4 at once I get a pretty unpleasant "coming up" feeling for about 15 minutes. I usually just have 2 a day, and I'd recommend people start with 1 just in the morning.