The code suggests that all effective CRCs for +-5 sectors x 588 samples are calculated, even if the calculation is efficient (it uses a one calculation at 0 offset, then derrives off that):
private const int _arOffsetRange = 5 * 588 - 1;
public void FindBestOffset(uint minConfidence, bool optimizeConfidence, out uint outTracksMatch, out int outBestOffset)
3891 {
3892 uint bestTracksMatch = 0;
3893 uint bestConfidence = 0;
3894 int bestOffset = 0;
3895
3896 for (int offset = -_arOffsetRange; offset <= _arOffsetRange; offset++)
3897 {
3898 uint tracksMatch = 0;
3899 uint sumConfidence = 0;
3900
3901 for (int iTrack = 0; iTrack < TrackCount; iTrack++)
3902 {
3903 uint confidence = 0;
3904
3905 for (int di = 0; di < (int)_arVerify.AccDisks.Count; di++)
3906 if (_arVerify.CRC(iTrack, offset) == _arVerify.AccDisks[di].tracks[iTrack].CRC)
3907 confidence += _arVerify.AccDisks[di].tracks[iTrack].count;
3908
Perhaps Gregory can give insight.