Derive it from your own historical stage-to-close conversion rather than importing a 3x or 4x rule. Coverage is just the inverse of your win rate from the stage you count from — so the ratio is only meaningful once you state which stage counts as pipeline and over what period.
Most coverage arguments are definitional, not performance-related. Before comparing to any benchmark, check that the denominator, the panel, the statistic and the time basis all match — most published comparisons fail on the first or the third of those checks.
Every claim above comes from work LeanScale published. These are the sources.