Why did toolmakers discard many pieces of stone while making tools?

Toolmakers discarded many pieces of stone during the manufacturing process primarily because stone is a difficult material to manipulate, and achieving the desired shape and sharpness often resulted in a high number of rejects. For instance, some indigenous groups have been observed rejecting as many as 300 pieces of flint for every single finished tool.1

The production of stone tools involves the intentional removal of flakes from a stone matrix, or core, to create a specific implement. During this process, toolmakers often produced "trimming flakes" or debris while shaping the core or refining an edge. While some of these discarded flakes were later utilized as flake tools, many pieces were simply abandoned because they did not meet the required specifications for the intended tool. Furthermore, early humans often made simple tools on the spot to serve a specific, immediate purpose and discarded them once they became blunted or were no longer needed. This high rate of discard, combined with the durability of stone, explains why such vast quantities of lithic artifacts have been recovered by archaeologists.2341