Location is a big factor in distance. Where have you been flying your drone? When you say furthest, is this when the video has dropped out or when the RC has lost communication and auto RTH initiated?
I live on the outermost of edge of a very small town, (4500 people) and my longest flights have been from my backyard. Past my house it becomes very rural, cow pastures and woods mostly. I generally fly till I lose video, then try to adjust my aim at the copter till I can regain video. I haven't been continuing without video feed, but it generally seems that once I lose video, control is lost soon after.