The expression SUM(A1:Z1000) is just 12 characters long, but it mentions 26,000 cells. Encountering such a term in a formula will cause an explosive fan-out in a discrepancy analysis.
OAK therefore provides the means to specify a limit beyond which formulas have terms that mention lots of cells are not further processed in a discrepancy analysis.
If this facility is enabled, and the default limit of 500 cells accepted, then the addresses mentioned in a range of up to 500 cells will be included in a discrepancy analysis (and, potentially, their precedents also); but ranges involving more cells will not be included in the analysis.