The variation you didn't write down is the variation you didn't get paid for. Log every verbal direction, scope change and delay the minute it happens - and watch the unclaimed number until it's zero.
This is a practical site-management tool. It is not legal, engineering or regulatory advice and does not guarantee compliance or a satisfactory inspection outcome. Requirements may vary by jurisdiction, project, contract and circumstances.
The tools above are free and yours to use. When you need the paperwork behind them reviewed by someone who has run sites, Obras HSE Services is a live consulting business in south-east Queensland.