In my seven years of training jiu-jitsu, I've never taken a single private lesson.
It's not been because I had anything against private lessons, much less the incredible black belts who have been available to me since I began training. It just always seemed like I was having a difficult enough time practicing and drilling the techniques I was learning in class anywhere from two to four times a week. Wouldn't a private lesson fall prey to the same challenges as my main lessons, all fundamentally dependent not only on the talent of the teacher, but also very much on the determination of the student to faithfully practice what was preached?
Unsure that I would have such determination - or at least, determination above and beyond the determination of mastering my every-other-daily lessons - I always thought that I would end up wasting the money of a private session, a sum I estimated as near a whole month's worth of training.
That said, I think there is one scenario in which I might find myself stepping up to the private lesson plate and, to be frank, it came to me shortly after training with Professor Rodrigo for almost 20 minutes tonight.
If you have the opportunity to learn first hand a technique - or even better, a concept about a technique - that no one else seems to be aware of, then that's the ideal time to take a private lesson from that person. To the extent that jiu-jitsu versus jiu-jitsu training (not necessarily the original intent of jiu-jitsu, of course) is increasingly a war of novelty versus novelty (from 50/50 guard to berimbolo sweeps to ...), learning a unique approach to a technique is invaluable.
In other words, if you have the chance to have a private in which Roger teaches you the cross choke from mount, Marcelo teaches you taking the back, and Prof. Marcio Feitosa teaches you passing the open guard, those are the privates you take.
I won't spill the beans on Professor Rodrigo's secret weapon, an attack I've seen very, very few others execute successfully. And just because I haven't mentioned Prof Carlos and Prof Alex doesn't mean that I haven't been doing some real intelligence work there, as well. And come 2013, I will looking to take this spycraft out of the cold.