In the past 2 weeks I have had people call in to advise me that they were moving. Each time neither had any idea but the change caused a significant drop in their auto rates. Todays rates (especially auto) are determined by many factors, unlike the old days when you just avoided a red car that was considered high performance. As in any good business insurance companies continually are reviewing the business to properly assign risk. What county you live in, what state you live in, the safety rating on your car, and how far you drive to work are just a few of the factors that figure in.
So, long story short, pick an agent that you like. To maintain you and keep you at the best rates that they can offer you will need to talk to them. Your agent should never try a one size fits all approach, and in order to do any differently you will need to feel comfortable giving them all the details.