Maybe you need to change your access point to mint's? I drove from Oregon to Michigan and back and the only bad spot was in areas that just flat out didn't have any service. All the MVNO are deprioritized, Verizon's policies are the worst of the big 3. T-Mobile's policy allows for much more traffic so it's not nearly as noticable. AT&T MVNOs have almost no difference between themselves and proper AT&T monthly service.