While it might take me longer to progress w/ just 2 privates a month, I could be just as good of a martial artists in the long run, right?
Of course! Do what you can, practice outside of class, and you will progress. There is no set minimum that you need to attend in order to make progress. Everyone is different. One person might need a lot of attention from the instructor, while another might do just as well or even better by comparison, even tho he has less attention from the instructor.
Generally, the more you train, both in class and outside class, the faster you will develop. But like most of us, you gotta find time in a busy life, so nothing's perfect.
Typically, I generally meet with my instructors only 1-2 times a week, and it's been like that for me from the beginning. We generally have small groups so it can almost be like getting a private lesson. But I also train outside of class a lot, often two and even three times a day. Practice your basics, your kata, work your techniques even if it is only in the air, train on the heavy bag to develop power in your techniques.
When I suggest the heavy bag, I do not mean dance around and spar with the bag. Don't work the bag like a boxer. Work it like a martial artist. Develop your individual strikes and kicks on the bag, keeping good form and good technique and good stance. And take your self defense techs and work them on the bag. It's not the same as on a person, but take the striking sequences and combinations that are in your SD techs, and work those on the bag, again paying attention to proper stance and postioning and such. Sometimes when we work a tech on a live partner, or in the air, we don't realize what it is like to strike something full force. It feels different and often does not flow quite the same, so it's good to play with this stuff on something like a bag that you can strike without causing injury to a training partner.
Do what you can and you can get a lot out of your training, even if you are not able to attend sessions as often as others can. Don't fall into the trap of comparing yourself to others. Just train and grow.