I definitely agree that in terms of effort expended implementation is almost always >=50%, but effort can be of various types. Sometimes when I've implemented ideas, the implementation took 90% of the time, but it was basically straightforward code-slinging, so I wouldn't credit it with more than 10% or so of the total intellectual effort expended on the project. Other times, important stuff does come up when implementing that sheds new light on the idea (or shows that it wasn't as fully developed as I initially thought).
When I'm implementing someone else's paper, a heuristic I use is something like: did I "just" implement this paper, or did I learn important things while implementing it that aren't actually mentioned in the paper, and which I should probably write up somewhere for other people's benefit? Sometimes the answer is "just implemented" even if the implementation took a long time and was hairy.
When I'm implementing someone else's paper, a heuristic I use is something like: did I "just" implement this paper, or did I learn important things while implementing it that aren't actually mentioned in the paper, and which I should probably write up somewhere for other people's benefit? Sometimes the answer is "just implemented" even if the implementation took a long time and was hairy.