Shadowing for six months is overkill and a waste of you time that could be better spent doing other ECs. If it's say, 60 hrs over the six month period, that's fine.
SDNers should be aware, as the wise Homeskool points out, that the purpose of shadowing is that you need to show Adcoms that you know what a doctor's day is like. Scribing is both employment and shadowing, and patient contact experience combined. Well, it's glorified shadowing in my eyes.
As we go into third year, I'm learning that the scribing experience varies widely from place to place. Some people, whether through a lack of initiative or the limitations of how their program is set up, get nothing more out of it than glorified shadowing. Others come out of it knowing how to write a full H+P, the standard approach to the most common things you'll see in the ED, and a lot of medical lingo (plus if they really like learning, a decent bit of pathophys from UptoDating the cool cases from each shift on the hospital computer). I still stand by my statement that I learned far more in 1.5yrs scribing than I have yet to learn in medical school...and by a substantial margin, too. That's not always the case, but it's
never the case with shadowing.
Either way, whether they learn to transcribe or to write a full note without being told what to include, you get far, far more out of an experience where you can't tune out the boring bits or the long bits, and where you have to at least read and pay attention to each patient's chart. We sometimes had students come shadow back when I was scribing, and because they interacted with the chart less, they got far far less out of the experience than I did. Just something to keep in mind.
Note: I also love shadowing, for the record, but you learn substantially less and it gets frustrating. I usually try to hit at least 3-5 shifts each block here in med school, though. You get to do more with it once you put on that short white coat...throw a few sutures, lance some gnarly abscesses, maybe steer a camera. Those things are fun, but nowhere near as useful as what I learned scribing, and that's with
good shadowing and some reasonable expectations of being allowed to participate as a student.