The question posed in the title is one that I hear frequently. And it's a good one, especially if you're using the DVDs without a teacher, as many people are. In a nutshell (in case you are in a hurry to get back to practicing and don't want to read to the end of the blog!), my rule of thumb is one song a month. There are, of course, exceptions. The exception to this, for banjo players, is "Banjo in the Hollow" which is so wonderfully easy that almost everyone gets it down pretty well in a week or two. But after that, it's back to one song a month. The other exception is young people, teenagers in particular. Many of them are simply going to blast through the material at their own pace. And I say let 'em at it. It's so much easier for them with their young, uncrowded brains. Plus, as I often point out, they have someone to cook their meals, wash their clothes, shop for their groceries and in general take care of the million and one things the rest of us grownups (or Grups as they said on Star Trek) have to contend with.
How did I come up with the one song a month rule? By observing (over the last thirty years) what my live and in-person students were managing to accomplish. Over a year's time, it usually averages out to one song a month. Twelve songs a year. Often it's fewer. And that's fine with me because as we all know Speed Is Not Important. Not even when you're learning new tunes.
Sure most everyone starts off like gangbusters, vowing to practice at least thirty minutes a day every day. But you know what? Life always gets in the way. Something happens that interferes with your banjo/fiddle/guitar/mandolin/bass/Dobro playing. (I like to call it "playing" rather than "practicing.") You get sick, someone in your family gets sick, you lose your job, you change jobs, your boss doubles your work load, you have to travel, holidays come up, you decide to add a room to your house, you decide to build a house. And on and on. Stuff happens. The idea of one song a month can keep you from freaking out and thinking you don't have time or energy for your music. Plus, when you start learning an instrument, I like for you to think of it not as something you're trying to learn in a specific amount of time, but something you will be doing for the rest of your life.
Sometimes I have the painful experience of running into students who tell me they have finished an entire DVD in a month. Yikes! Unfortunately when I hear them play, their idea of learning a song and my idea of learning a song are simply not the same. If you are playing out of time, having to stop and think about what you're doing, or simply playing sloppily then, in my book, you have not learned the song. You are still in the learning stage and should not move on to new material.
One of my newest students here in Winchester did that very thing. He got a banjo DVD from me and worked on it for several months before he came in for lessons. Alas! The songs had fingering problems, timing problems, and wrong notes. They were also not as clean as I like them. The good news is that, in spite of all these problems, the songs still sounded like music. I could tell he was hearing them as true songs and not just a string of licks. There was obviously a lot of talent there. Because he is a wonderful, straight-up guy who can take it on the chin, I told him he'd have to go back and do all the songs over. He was willing. So he went though several weeks of what Tammy Wynette calls "aitch ee double ell" unlearning all the bad habits he'd developed. As he realized, it would have been so much easier to learn them right the first time.
As I am constantly telling my students, these first songs are the foundation for everything else you are going to do on your instrument. Learn them right! It's all there on the DVD, in living color.
Of course, the one song a month idea is just a guideline. Its whole purpose is to keep you from trying to learn one song a week! So, if you are a beginner, how do you know when it's time to move on to the next song? Basically when you can play the whole song from start to finish a couple of times in a row at the same slow tempo without having to stop and think about what comes next or without having to stop and start over. Notice I didn't say anything about playing it perfectly. A few little mistakes are fine. (As long as you don't break time. That's a big no-no!) The important thing is to be able to keep the song going when you make mistakes. Playing a song perfectly doesn't happen too often, even when you are a professional. We just know how to cover our mistakes better! (One way is to pretend like we meant to do it that way!)
After you have a few lead breaks under your belt, it's time to start learning the chords. Then you should learn to swap breaks with someone---a friend or your teacher. Once you know the lead, the chords, and can play with someone else, then you really do know the song.
If one song a month seems, like, way too slow, just think. If you learn one song a month, you'll have twelve songs in a year---that's two DVDs worth of material. And after you have established your solid foundation, you'll probably find it's easier to learn more than one song a month. That's because many bluegrass songs have patterns that repeat and melodies that sound similar. Once you understand that, you will be off and running. But until then, remember: One Song A Month! (And don't forget to learn the chords!)