I ran into the following problem. I have some lengthy paper in which I develop some theory to attack some problem. While I was working on this paper, I got some nice result which might interest a bigger audience and can stand by itself (that is, it is interesting out of context of the big work, and has a fairly short proof).
The problem: should I write one long paper or two papers, one long and the other short? If I write just one paper, the short result will strengthen the paper, and it will be, perhaps, more whole. On the other hand, for someone that is only interesting in the short one, it will be better if it appears in a separated paper.