Interesting. I never thought about dividing engineers this way. I do know that the two best engineers I've ever met were slow. Not just slow in working, but slow in everything. Speaking, moving, etc. This frustrated some people, but these engineers saved everyone else much time and frustration because their work was rock solid, well thought-out, and complete.

And, once you accounted for time spent bug-fixing and validating things, they weren't actually slow.