It's true for many people....hence the chart lol. It's just an average/estimate, everyone's bodies and biological systems are different and work differently, so of course there is variance- just like any other drug. And of course, a particular body changes and develops over time, so you'll even start seeing a variance within yourself over the years.
So, by this rule, some people will react to a lower or higher dosage than others, or in comparison to other substances, and they may even react to the substance in very different manners from one person or substance to another (ie: people claiming clonazepam is "subtle"). Makes it all very subjective....but to a point.
You took a pretty hefty dose. Give it 2-4 hours AT LEAST to show some effect before redosing. Really, it'd be best not to redose at all. For all you know, your body reacts slowly to it, you'll go and redose, just to have the initial dose hit you like a freight train 5 minutes later and you're in blackout territory....come to the next day to hear all the crazy shit someone in your body and clothes did the day before....maybe see yourself on the news or find relationships or family destroyed....who the hell knows what a person blacked out would do...usually incredibly embarrassing at the very least.
Be careful.
-PA