Comment by angra_mainyu

I have to agree, particularly if you look at functions as pipelines: data/events go in, other data/events go out.

If I had to hazard some kind of heuristic with 99% applicability, it'd be to always strive to have code with as few indentations (branches) as possible. If your code is getting too indented, those deep Vs are either a sign that your implementation has a strong mismatch with the underlying problem or you need to break things up into smaller functions.