Theory of Constraints - your experiences, positive/negative? | Modeling | Forum

With the recent passing of Eli Goldratt, I had a thought the other day about the Theory of Constraints. It occurred to me that in TOC there is a subtle recognition that the “Drum” constraining resource is not necessarily the only constraint to consider. If it was the only constraint, why is a “Buffer” in front of it required? The buffer is there because upstream processes can become constraints themselves, and the TOC idea is to avoid starving the Drum for work. Upstream processes might be lesser constraints than the Drum most of the time, but using a system/approach that limits constraints in the planning/scheduling model seems risky to me. I understand that everyone wants things to be “simple”, but none of us want things to be “wrong” or cumbersome when reality varies from the normal planning model. What are your thoughts on constraints in a planning/scheduling model?