Certifications have dates. A technician whose qualification lapsed last month cannot work, and finding that out on the morning of a job is both a lost day and a serious problem if anybody had gone up.
Equipment is inspected and recorded. Every rope, harness and connector has an inspection interval and a life, and the record is what a client's auditor asks to see before work starts.
The paperwork precedes the work. Method statement, risk assessment and rescue plan are produced for each job, and reusing last month's without adjusting it is the commonest failing in the sector.
Sites repeat, so knowledge should accumulate. Where the anchors are, which roof access is locked and who holds the key turns a second visit into an hour rather than a morning.