Putting the layers together doesn't take much time at all. But what can take a while is silo'ing the part of the photo that's meant to go in front of the logo. It's all about how complex the edge of the silo is. If it's someone's wavy, frizzy hair, that shit is impossible. If it's a clean, close crop hair cut with a clean line around it, it's easy. As someone mentioned below, the more contrast between the background and the foreground, the easier your job is.

And yeah, I work in the industry. I work for a small publishing company in NYC that puts out specialty magazines you've never heard of.