I recently wrote that it didn't particularly matter that my most recent promotion was not particularly rigorous. I'm still of the opinion that belts don't count for all that much, especially when making inter-school comparisons, but after some more thought on the subject I want to present an argument in favor of introducing physical/mental rigor early in the training process. If you'll indulge me for a moment I'd like to recount an event from my past by way of illustration.
The first school I ever studied at really made you work for your belts. Tests took a couple of hours minimum, even for beginning students, much of which was spent under the supervision of junior instructors whose job was to exhaust you as much as test your knowledge. One of these tests, either 2nd to 3rd rank or 3rd to 4th, I don't recall which, stands out in my mind as an event of fundamental importance in my life second only to marrying my spouse.
At one point during this test the instructor told us to pick a partner and tell them about ourselves, all while standing on one leg with the other knee in the air. After a brief period, long enough for our legs to be tiring out, he came around and started asking questions: What was your partners name? Where did ey live? What kind of a computer did ey use? And so on. At a certain point the questions got so ridiculous that I stopped and said to myself "Hey, wait a minute, he doesn't actually expect us to answer these, does he?". Following quickly on the heels of that question was the realization that, if he didn't expect us to actually have answers, the only reason he was asking questions in the first place was to harass/fluster us. Thus I would "win" simply by not allowing him to fluster me.
It wasn't quite satori, but it certainly was an epiphany. That realization, that there wasn't any point in getting angry, and that I had a choice about whether I would do so or not, was the kicked pebble that turned into an avalanche. I could choose not to be angry. And if I could choose not to be angry I could also choose not to be envious, or presumptuous, or any of the other negative mental states that frequently beset MA practitioners.
In time (years) it led to the cultivation of what I characterize as a "receptive ego": I recognize my own worth, but I also recognize where I can benefit from the experience of others. That mode of being-in-the-world has spilled out into my everyday life to great benefit. I'm a better person now, and I choose consciously how to react to events (most of the time).
Now, coming back to my main point... I recognize that my experience is unusual, but I think there's something to be said for stressing people as a part of the training process. Students can become better martial artists, and even better people, if they acknowledge their shortcomings and strive to make themselves better. It would be great if we could systematically induce them to do so, but it seems to me that this is one of those areas heavily influenced by personal idiosyncrasies. At best what we can say is that pushing students physically and mentally will help at least some portion of them enter into this dialogue for themselves.