That's an interesting question. I'm usually not running in the middle of a large pack, largely because I generally don't run mass participation races. Where I'm running, I always find it better to key on the runners around me and be competitive than to focus on splits/pace the whole way. However, is the story different if you're in a pack?
I'd still say not necessarily. No, you're not intently focused on beating that one guy ahead of you because you might be in a steady stream of runners. However, if you're focused on competing, part of that is knowing how much you have left and how hard you can go. In other words, running by feel. To me, that's the best way to run anyway. You don't have to worry about precisely knowing before the race what your best performance is going to be and what your ideal splits would be to accomplish that. You can know how you should feel at the mile, at the halfway point, with a mile to go, etc. Secondly, late in the race, the clock is very much an abstract. Passing the person immediately in front of you is very concrete. Even if it's a steady stream of people, you can still see how many people you can pass in that last mile or the last 3 miles or whatever. This is something that's right in front of you the whole time and you can draw strength from.
As an example of a race I ran where simply competing was the best option for me, I think of the inverse of running in middle of a steady stream of runners. I think of my last race of 2011. If you recall, my only goal was a sub-17 5K. How was I going to accomplish that? I'm sure a lot of people would say strap on a Garmin and run 16:59 pace the whole way. Instead, I competed. Even though I was all alone with nobody within 2 minutes of me, I went out and ran like someone was right on my back the whole way. I ran as hard as my legs would allow and the result was far better than a 16:59.
By the way, just saw this posted on Twitter. Interesting timing.
Food for thought: When Khalid Khannouchi broke the marathon WR in 2002 with his brilliant 2:05:38 at London, he was not wearing a watch.
I also remember his 2002 Chicago race where he ran 2:05:56. After the race, he said time wasn't even among his concerns. He waited to make his move until he knew he could go for the win. I took a look at pictures I took during that race (not the greatest quality) and Googled other pictures of that race and other races. No watch in any of the pictures I've found.