Claims and disputes
The record is written before the job, while it runs and when it closes, so the answer is already there when someone asks.
Nothing to dig for
Skip the search through photos, mails and old folders. One job, one record, open in seconds.
Written while it was true
Made as the work happened, not remembered afterwards by people with something to lose.
Facts, not memory
Who was there, what they said they would do and which conditions they met.
Changes count too
Extra work, a change of scope, an unexpected cost. Say it on site the way you say everything else, and it lands in the same record, timed and signed by the people who agreed to it.