Darin (Bowman) and myself are the grusome twosome - we usually always hunt together. We always hunt fields. As a matter of fact, we will stand right out in the open in the middle of a field and call. Like everyone, we have good nights, great nights and piss poor nights.
As Darin (Bowman) stated in his post, our best times are from dusk until about 9 or 10 pm. We hunted hard the other night until almost 2 am, hitting numerous farms and only called in 3 fox...none of which we even got a shot off at. Thats why its called hunting! I don't think we even seen an eye after 10 or 10:30. We were hunting some farms that were well over 200 acres and not a single eye.
Its all about getting out there and finding out what works for you in your areas. We have pretty much all red fox, perhaps areas with grays are diffrent. Its all about putting your time in the woods !! Just my opinion.