“Connected processes force all team members to strive for perfection. [Toyota Manager] Ohno taught that lowering the ‘water level’ of inventory exposes problems (like rocks in the water), and you are forced to deal with the problems. Coupling steps in the process so that there is little material or time buffer lowers the water level and exposes inefficiencies that demand immediate solutions. Everyone concerned is motivated to fix the problems and inefficiencies because the process will shut down if they aren’t fixed.” 

The Toyota Way 2nd Edition by Jeffrey K. Liker (McGraw Hill, 2021) p. 62.