I used to do both rimfire and CF benchrest. Conditions identify the real shooters quickly; I was never among them! We used flags with propellers, and they worked well. But, trying to identify the same condition for each shot is a real challenge, especially with one eye on the clock. My best results were usually just trying to wait for something as close to calm as the day would offer, and then rip off a group quickly. I shot only group competition, so reading the wind perfectly wasn't as critical as in score shooting, but consistency was more important. Doesn't make any difference where the group is, as long as it's one hole. On the other hand, one bad shot doesn't necessarily kill you in a score match, but it always will in group shooting. I can't say that any one wind condition was the most difficult for me, trying to find consistency was the elusive quarry. Nowadays, if the wind blows, I throw a tin can down range and try to knock it around from positions. Fun to watch and listen, and no paper trail to show my incompetence!