Turboe,
My regular weekly group is a floating foursome which usually runs the gamut of abilities-- It is not uncommon for us to have a 3 Index and a 3O+ Index in the same group. We play very early in the morning and often have no one in front of us. The course (Rustic Canyon) plays at 6900 yards, and has 3-4 long walks between tees, and plays half up a slight incline and half down the same incline. We walk, we wager, we screw around a little. We hit provisionals, we take our time on a few key shots. While we almost always play some sort of matchplay, most of us hole out for handicap purposes. One of the regulars always starts his wristwatch timer on the first tee, so I have a very good idea of our pace over the last 4 months.
I havent figured out the exact average time, but most of our rounds have taken between 3:40-3:50. Our slowest round has been 4 hours, but we wrote that off to fog-- we couldnt see a thing for the first 9 holes. Our fastest with a 4some is a little under 3:30. Our back nine usually takes about 15-25 minutes longer; probably a combination of the longer distance, a few long walks (including a long walk to 10), lots of bullshitting, and the fact that we are usually well ahead of the group behind us, and enjoying a beautiful morning with the course to ourselves.
We make it clear to anyone we invite to play that they have to do what it takes to keep up and play a 3:45 round. If they lollygag even a little we don't invite them back.
I have never bought the theory that bad golfers play slower. I personally was as fast or faster when when I couldnt come close to breaking 110. I am glad to finally have some actual times to back it up (the timekeeper is the 30+ Index.)
Contrary to Shivas' 2-3 minute estimate, I have no idea why it should take any more than 30 seconds to address the ball and hit the shot. So if a hack hits 40 more shots than a scratch, that only adds 20 minutes to the round. And Hacks are much more likely to move along when need be, while the scratch is probably going to go through his "routine" no matter what the circumstances. Plus, if a hack is taking 30 seconds to putt, he/she is wasting everyone's time, including his/her own.