Level 70-80. Ok, now you are in one of the most difficult aspects of leveling your the fletching. You'll need to make 8323 Yew Longbows before reaching the level of OSRS gold 80. The only thing I have to say is my very best wishes, since that's quite a few bows.

Level 80-85. You have the option of staying with Yew Longbows and/or changing to Magic Shortbows. Magic Shortbows offer more experience, if you are buying logs. If you are cutting your own logs, then even at 99 woodcut it's faster to make use of Yew longbows instead of Magic Shortbows, as Magic Logs are more difficult to cut.

If you decide to stay with Yew Longbows, you'll need to create 8,484 of them. You'll need 7,620 Magic Shortbows to progress to level 85 if you want to create Magic Shortbows. Congrats! I think it's time to go and take on something new. Perhaps alchemy. Sell all your bows, buy something more elegant, or buy RuneScape gold acquire new techniques. Only serious flytchers should continue beyond this point.