The consideration is if possible reduced the time required to search tools, screwdrivers, wrenches can be reduced. The next question is “What is the variation in the screw tightening operations can be combined? So one tool can be used for a screw.
Seiri, Get rid of as much as possible tools that can be replaced by hand. That is what must be considered in lean manufacturing. Getting rid of the equipment here does not mean eliminating a tool that should reduce the burden on humans in performing their duties, but if the equipment can be replaced with empty hands, why not be done. Conversely, exclusion of this tool should help workers complete the task quickly.