Most ad-hoc timing code in Python looks like this: start = time . perf_counter () result = do_work () elapsed = time . perf_counter () - start stats [ name ]. append ( elapsed ) It works, until do_work() raises. Then the line that records the timing never runs, the exception propagates, and the one call that was probably slowest — the one that failed — is silently missing from your stats. If you're using timing data to find what's expensi...