No kidding. Particularly after reading that you should not submit an
insurance bid request to more than one agent since "they all use the same
underwriters". Recently I submitted one to Avemco and immediately got an
email saying they wouldn't cover. Falcon came back with a bid on the same
coverage request within a half day.

Avemco isn't an agent. Avemco is a direct insurer. They aren't talking
to anybody but themselves. An independent broker will shop your quote
(potentially) to several underwriters.