Much beyond that point (moving water) you may have to do a lot of mending in the early part of the cast.
Fred, good point! That's why I said accurate casting is more important. I know from my own experience when I was learning, I would get too much line out on the water, and no amount of mending would correct poor accuracy. Mending is a technique of line control, but if a cast is so far off the mark to begin with, the current usually takes the line & fly so far off target before the angler can respond that it becomes a futile effort.
BTW, my idea of accurate casting at any distance is within 4" to 6" of a target consistently.
Funny, but back in Sept. I had a situation casting to a moving Redfish on a grass flat where I was making 75 to 80' casts with an 8 wt. The fly landed all around the fish, but I couldn't seem to get it in front of it. Had I been able to move closer it would not have been an issue, but the tide had started to fall & that fish was moving fairly quickly towards deeper water. I lost the opportunity to hook up with that fish simply because I could not make an accurate cast in front of that fish at that distance.