Again, my experience with our region is slightly different (we've taken this thread off topic enough, I assume). Once a student has demonstrated a capacity to be safe and consistent, I am (and I don' want to speak for the rest of my Pacific Region cohorts) more than willing to sign the student off to go solo for the rest of the day*, with the provision that I am always available to jump back in the car should he or she require it. Of course, our events being more expensive than just about any other organization short of the Russels and Skip Barbers of the world, means I ENCOURAGE the student to keep me or at least an instructor in the car because that's what they paid for. Heck, if I were to sign up as a participant for a BMW CCA school, I'd want to keep an instructor in car even at my current speed and level, simply because there's ALWAYS something I can learn from each instructor.
But I fully agree. We are bound by some very strict rules passed down by National. There are certain minimum requirement, such as having an instructor be available to any participant at any time, or passing only with a point by, has made BMW CCA events somewhat less attractive to participants who are only looking for hot-laps. However we've worked within the CCA guidelines as well, by altering our passing zones (for certain tracks, it's defined as 'from the back of the finish line to the front of the finish line') while still maintaining the passing only with a point. A+ students now ONLY drive with an instructor for a 15 minute check ride in the morning and are to go solo for the rest of the day (however we still require anyone signing up for A+ to be screen and by recommendations from an instructor at a prior event) with most of the coaching done in classroom. This new "standard" is being accepted and implemented nearly nationwide.
I agree with the fact that BMW CCA is far more conservative than most of the other organizations you'll find, in just about any region. But part of that "tight ship" mentality is also what attracts some of our participants, who's often got a $50,000+ car that wants more of a learning environment than simply open lapping and are willing to pay more for the instruction.
Different strokes for different folks if you ask me.
*p.s.: The caveat re: SOLO. I wouldn't necessarily sign off a student if he or she has more to learn within the confines of the group. If I feel there's more value to be had for the participant by having me in the passenger seat, I'll stay and dial my instruction back even if said participant is fast, safe, and consistent. I may have him/her try alternative lines, start working on other more advanced techniques, or work on aspects of driving not taught through the normal curriculum. Unless there's absolutely nothing more I can offer, I often encourage the student to keep me in their car.
However, if there truly is NOTHING I can offer the driver...Well, we might as well swap seats and have HIM/HER instruct me.