I'm revising a story for an editor right now. The process is never as straight-forward or as easy as I'd like it to be. Every time I make one change--to the plot, or to a character--it results in a whole host of related changes that have to be made.
It's like my story is a jigsaw puzzle. Each piece has to fit with all of the other pieces. So when I change the shape of even one piece, it doesn't quite fit with the other pieces anymore and I have to reshape several other pieces to make everything fit together again. Frustrating at times, but ultimately satisfying when the new puzzle is solved.