Most bows are rated at 28", for comparison purposes and because that is a common draw length. The actual length a bow can be drawn will vary with the bow. A short bow, say a 54" recurve, might have a maximum draw length of 27", while a longer bow, say a 64" recurve, might have a 32" maximum draw length. The actual recommended draw lengths will be specified by the bowyer and may be more or less than the examples I used.
If you're shooting a recurve, and you don't draw it enough, you're not working the recurved part of the limbs and you're not getting the full efficiency out of the bow. If you draw it too much, the bow begins to stack (I'm not sure if this is the same thing as "loading" or not) which means that the draw weight increases disproportionately much for each additional inch that you draw the bow.
The bottom line is that you want to find out from the bowyer what is the maximum recommended draw length for your bow, and not draw it past that, or your shooting will become erratic and it won't be enjoyable to shoot the bow. You do want to draw it close to the recommended draw length, so you get the maximum efficiency out of the bow.