As a underwriter, I know almost all companies at insurance market honour their quotation for 30 days.

A insurance agent get the quotation from company for his client. The client need time to think about it.
Or,
Compare the quotations from different companies or brokage.

If he has not asked this coverage until the expiry date and over the valid time, he may face the problem to renew his insurance.

So remember, be on time.