A standard form has a ceiling
Above a certain value, mainstream homeowners products stop fitting: custom finishes, specialty construction and long rebuild timelines are not what they were priced for. High-value carriers exist for exactly this and they underwrite differently, often with cash settlement options and no coinsurance penalty. Being on the wrong form is the real risk, not the rate.
Visible assets attract larger claims
Liability exposure scales with what a claimant believes is reachable. At this value, a standard liability limit is a rounding error against a serious injury judgment, and an umbrella is the layer that makes the difference. It is usually a small fraction of the underlying premiums.
Art, jewelry and collections need scheduling
Sub-limits on a standard form are measured in thousands regardless of the overall coverage. Scheduling each item with an appraisal removes the cap, usually removes the deductible, and is the only way the policy reflects what is actually in the house.