A dock inspection should always be completed during a real estate transaction. This is so you understand the condition of the dock before purchasing. Typically, home inspectors charge less fees for the dock inspection when coupled with a general home inspection. This is so you purchase the home/dock for a fair price.
However, general dock inspections once owned, should be inspected yearly for damage. Docks should be properly maintained to protect from further damage during heavy rain/winds/waves. A damaged dock can possibly damage seawalls and your home’s structure.