Myrddin uses 10 aspiration windows (or "steps", if you prefer) before expanding to a full-width search. It starts at +/- 16cp, but slowly grows larger, such that the last step is plus-or-minute (but not both) 720cp before going full-width. In other words, if the search continues to fail high or low, requiring expansion of the window, the last search will be either -16/+720 or -720/+16. And, as I said, it takes 10 fail highs/lows to get there.
What do other engines do here? The main thing I'm concerned about with testing is if, for example, I reduce the number of steps to 5, that very fast time controls commonly used in testing won't exercise this change much, if at all. The change will definitely affect CCRL 40/40 testing - but who has that kind of time?

Any thoughts? Maybe the better question is how far away from the midpoint in cp should the search get before going full-width?
jm