I was thinking about this.
In the story I'm currently writing, SH, I'm only about two chapters in. I have introduced a character named Kam and I am stuck. I think the problem is that I introduced him too soon. He's an interesting characters, and at first I thought this situation that the main character is in would be a good place for to introduce him.
Now I'm not so sure.
There are writers out there who follow an outline very strictly. Others don't start with a outline, but do work in a linear fashion. They start with their prologue and continue through chapter 1, 2, 3 until they reach the last chapter X or the epilogue.
Some start at the climactic scene and work backwards, perhaps focusing on the main scene and then filling in the smaller ones and the transitions.
I tend to write in a generally linear fashion, often because I haven't the foggiest idea how things will end or what the actual climactic scene will be. But one habit I do have is this: when I get stuck, sometimes I just stop and skip ahead to the next scene that is fully formed in my head (that I can picture the action, even if it isn't one of the more important scenes). The gap may be just a page or two to wrap up the troublesome scene, or a whole chapter.
I try to leave the smallest gap possible and just type in a note to myself that I need to fill it in later. I did this with my Honors thesis. I started that story in high school, worked until I reached a point and then needed to stop in order to focus on classes. When I took up the story again (this all before even joining the Honors program) over the next summer, I didn't know how to wrap up that scene I'd left off on. So I just skipped ahead, from that beginning of their procession, the first night away from the castle to their first major destination. I didn't know how much I was leaving out, but it was sort of a fresh perspective.
I tend to think, while, as always, it may not work for all writers, that skipping ahead is a helpful solution to getting stuck. I think it may help me with this new problem (just jump ahead to the rescue and maybe try it without Kam. If it flows better, maybe they need to meet him later).
It gives the writer a chance to step back and see how the story could work better from a different position, and reenergize him/her to write again. See how it works. I hope it helps.