A person or algorithm that compensates for lack of sophistication or native stupidity by efficiently following some simple procedure shown to have been effective in the past. Used of an algorithm, this is not necessarily pejorative; it recalls "Harvey Wallbanger", the winning robot in an early AI contest (named, of course, after the cocktail). Harvey successfully solved mazes by keeping a "finger" on one wall and running till it came out the other end. This was inelegant, but it was mathematically guaranteed to work on simply-connected mazes - and, in fact, Harvey outperformed more sophisticated robots that tried to "learn" each maze by building an internal representation of it. Used of humans, the term *is* pejorative and implies an uncreative, bureaucratic, by-the-book mentality.
See also code grinder.