CHECKSIGFROMSTACK(VERIFY/ADD)

The emphasis is on the importance of not modifying legacy Script unless absolutely necessary. Such modifications could potentially make it more difficult to reason about and understand the implications and behaviors in extreme conditions. This approach suggests a conservative strategy towards changes in legacy systems, highlighting the need for meticulous evaluation before implementing any alterations that could affect the stability or predictability of the system. This perspective underlines the complexity involved in managing and upgrading legacy code within critical systems like those used in blockchain technologies, where security and reliability are paramount.