Rejected Key Schemes
In the previous section addressing the design decisions for the 2/5 scheme, human error was listed as a reasoning for the 2/5 design. Suppose that a 3/5 or above scheme was used, and cryptographic parts were lost, the risk of losing funds would increase significantly as well.
The 1/5 scheme simply does not work because if one of the cryptographic parts were to be compromised, funds would be lost.