There is no precise, scientific answer nor is there a reliable “rule of thumb.”
Liability coverage isn’t purchased for the average rather for the catastrophic-type loss that could jeopardize one’s personal assets.
Has your net worth increased over the past 5 years and have you increased your personal liability coverage to reflect this increase?
In response to increasing net worth many of our clients have purchased personal liability umbrella coverage.
Umbrella coverage sits over the liability protection on their personal autos and homes and is relatively inexpensive.