How often do insurance companies check driving record?

How often do auto insurance companies check customers driving record? I was under the impression that they check your record each renewal period. However, a friend of mine told me she got a DUI a few years ago, but her auto insurance rates were never impacted. I assume that means they never checked her driving record in the three years after her conviction.

If this is the case, which insurance companies are the least likely to frequent examine a customer’s driving record?