Good lawyers know when to talk and when to be quiet. Being quiet is the toughest part because lawyers want to fill the room with their eloquence, which is often anything but. And talking too much can take away from what you are trying to say. It can hurt your case.
It is important to know when you've said enough. I had a hearing today where I said just enough. Then I didn't say anything else. The expert concluded my client couldn't do his past work, and he had no transferable skills (she said yes to the judge's question about transferrable skills--always a wise sign). The expert concluded no jobs were available. Both of these things mean--barring a dramatic shift in opinion--this client won his hearing. No need to say anything else when you've already won.
I didn't talk too much, and I said much more by doing so.