A nightly job drifted from 30 minutes to 5 hours over six weeks with no code change. Find the cause.
The regression with no smoking gun, no deploy to blame, no single bad night. Staff-level triage is about reading the trend, not the last run, and the four slow-burn causes that a one-night comparison can't see.
Updated Sep 2026 · Grounded in real Forward Deployed Engineer interview loops and written to a senior-engineer editorial bar.
The regression with no smoking gun, no deploy to blame, no single bad night. Staff-level triage is about reading the trend, not the last run, and the four slow-burn causes that a one-night comparison can't see.
Lead with where the obvious approach breaks, because that is the judgment they are screening for — most candidates jump straight to the happy path and lose the room.
Then walk the failure back through the pipeline in order, naming the one metric the customer's exec sponsor actually cares about before you propose the fix.
