20,30 & 40.

I know where the question comes from..... and maybe you' re right. With todays modern flat shooting equipment the difference between 20 and 30 is closing.(As evidenced by all the one pin shooters we have). Beyond 35 all the bows start to show the spread more and precise aiming may be more critical. I went with even numbers after starting with 15, 25, 35 years ago. I did it because i started shooting NFAA rounds with 5 pins and wanted all the aiming points I could get to 80 yards with only 5 pins. Of course in those days 215 was flat out lightning speed. If I had more time I might be tempted to go back to 25, 35, 45.... prompted mainly by your question.... but I' ve been shooting the even numbers so many years I' d need several months of practice to avoid calling my 25 yard pin my 20 yard pin and blowing an otherwise easy shot at say 27 or 28.