A broker would normally have an Umbrella book, where all their clients share the risk and premiums are pooled together. Your short term policy can get protection within the Umbrella..when you had a few claims but the Brokers Umbrella Premium/book remains feasible you may get immunity from big increases or cancellations because the Umbrella premium is bigger than your individual premium and your Broker may negotiate for you based on the Brokers book value vs your individual premium in return that you manage your risk better.