Well im from south Devon and the hares round here can only be ran on the lamp as the fields are to small with to many gates and runs, most dog after a season or 2 learn to scoop them up quick, ran hares in Norfolk with my dogs fitter then they have ever been and they didn't come close to one of them.
Mate came down from Norfolk whose dogs pick them up there easy yet didn't come close down here well 2 different people.
I think it all depends on what cross and where you run them.