It's no different over here TBH. Although there are brokers (and broker websites) that will poll a number of major insurers for their best prices, there are always great deals that you only hear about after the event. I could be wrong but I think that the insurer's "risk" parameters change regularly and it's pretty much a lottery at renewal time as to how they assess the risk that you present them.

At 43, and with a full NCD, I thought that I was (give or take) pretty much at my full discount level no matter where I took my business but I've noticed much younger drivers driving faster cars for the same money! Having said that, I suppose that their excess penalty could be a lot higher than mine, I don't know.