But there is still a lot of assumption of what techniques were used. What we know is just the tip of the iceberg. I will make an assumption that not all ancient people were specialists in all areas of crafting. Like the members of this group. Some are amazing knappers, some are amazing bowyers. Some are even amazing leather workers, carvers, weavers, fletchers... You get the point. How many are amazing at all of these. Not many, if any. Given the time most of the members here can make any amazing product they put their minds to, but they aren't worrying about procuring materials to make their crafts on their own two feet, as well as obtain food, as well as protect their families. I don't know anyone who relies on these hobbies to live. As in protection as well as gathering and processing food. Were ancient knappers chosen to do it because they had a natural ability to do it well, as well as quickly? Let's also not forget that these arts died as soon as they weren't a necessary part of existence any more. Sure, a few people carried on the tradition, but what was lost from one geration to the next in the waning years. It is safe to say more information has been lost to the sands of time than what we have relearned since it was customary to use stone tools. Patrick's scale may not work for everyone, but as long as it helps him, that is all that matters. It seems to make sense to me. Just because it isn't what you know, or doesn't make sense to you, doesn't mean it isn't something that will help someone else.