I don't think there is any one or right answer. You have to know the range, and the only way you can learn it is by shooting on it. You're looking for two things.
The first is what gives consistency. If the flags are pointing in a certain direction & the tails about the same level, and all shots fired in this pattern group well, you have something. When I started shooting, it was club matches at a local range. We shot every month. In time, you learn. I used 3 flags at 100 yards. When the last two were pointing basically left to right -- say, pointing at 8 o'clock, and the closest flag was pointing mainly right to left, say, pointing at 4 o'clock (tails about the same height), you could shoot a good group, just about every time. At that range, that was a good condition, month after month. Other ranges will differ.
The second thing you look for is "how often" a condition occurs. I remember a 300 yard match at Charlotte, where I just couldn't get bullets shot in the right to left pattern to print the same. But the left to right was pie; I could shoot real small. Problem was, the left-to-right pattern wasn't there very often. What to do? Since I couldn't figure out the common condition (right to left), I shot the far less frequent left to right. I did win HV that day. But you could argue that was stupid, if I could only have figured out the R-L condition -- as others did -- I'd have had a better 4-gun.
FWIW
