It depends where you are in your lifting career.
All else being equal (diet, training, supplements, etc.), a newbie lifter will gain much more muscle over time than an advanced lifter will because of dimininishing-returns effects. Muscles that have never seriously been stimulated will grow more easliy and faster than ones that have been extenstively stimulated for years.
In addition, very advanced lifters eventually approach their biological limits, making it very difficult to achieve even modest gains. For them, 10lbs/year is a good gain. Newbies can gain significantly more weight in a year -- there are people here who've gained 50lbs in a year.
In addition, the pound-per-week guideline is weight gain, not LBM gain, as I understand it. The guideline should lead to optimal LBM gain, but not all of that will be LBM. If you're gaining significantly more than that, however, you're likely gaining too much fat. If you're gaining significantly less than that, you're likely not eating enough. But see how your body responds to diet and training and adjust accordingly.
Finally, if you're a true novice you probably can gain LBM and loose fat at the same time (if you're not lean) which means that its possible to gain LBM while not gaining weight.