I failed to understand concentration meditation when I first did it. Aleister Crowley, in his instructions for concentration meditation, suggested that it would be sufficient to do it for only 30 seconds or five minutes at first. He failed to specify that “at first” could very well mean, “for the next seventy years.” Nor would that make you a bad meditator.
Consider that understanding a new mathematical concept usually requires nothing more than a split second of intense concentration. But getting in the position to have that split second of concentration is really hard. Holding your mind in the right position for even that long is a hell of a task.
It takes most people years to learn algebra. But how many conceptual leaps are really required to master that task? Probably five minutes’ worth of genuine conceptual thought would be enough. But I don’t think it speaks badly of our children that it takes them years to pull that off.
So let’s consider concentration meditation within that general frame. Genuine concentration is something that a genius might do for a split second, half a dozen times a day. So in concentration meditation, the goal is to achieve just one of those split seconds. It’s clear that for this goal, the amount of time spent meditating is absolutely immaterial.
Trying to maintain continuous concentration for thirty minutes is absolute insanity. You’re not gonna do it; you’ll just redefine “concentration” so that now it’s something you can do for thirty minutes. If your goal is concentration meditation, I’d say it’s better to have sessions around five minutes. Don’t even bother timing them.
Be satisfied if you achieve one split second of concentration. And once you have that moment of satori, if you just remain open to its echoes, then it will transform your experience in all kinds of wonderful ways, so that its value goes far beyond that of a mere momentary experience. (A mathematical discovery does not cease to have value once the moment of discovery is over; and the same is true of satori.)
(Note that all of this applies specifically to concentration meditation. Relaxation meditation is an entirely different game; you can reasonably do that for as long as eight hours.)