The new Lean question is not “How little?” but “How robust?”

Lean has had an impressive track record in many companies. It has made processes more transparent, exposed waste, and helped organizations work more closely with the value stream. But the same thing happens eventually with every successful management concept: it gets simplified.

In many places, Lean has become a business “diet.”

Less inventory. Higher capacity utilization. Shorter lead times. Less employee retention. More metrics.

Some of this makes sense. Lean without the goal of reducing waste would be arbitrary. But Lean without an understanding of the system becomes dangerous.

The central question for 2026 is therefore no longer: How little inventory can we afford? The better question is: How robust must our system be to deliver reliably under real-world conditions?

This shift is crucial.

In a stable world, processes can be tightly scheduled. Delivery times are reliable, demand is predictable, workforce availability is plannable, transportation routes function, and suppliers deliver as agreed. In such an environment, low inventory and high capacity utilization seem logical.

But many companies no longer operate in this world.

They deal with volatile demand, uncertain delivery times, a shortage of skilled workers, geopolitical risks, energy price fluctuations, regulatory requirements, and high expectations for on-time delivery. In this environment, a system that is optimized too tightly can collapse.

In its Global Supply Chain Leader Survey 2024, McKinsey describes how supply chain challenges remain widespread. Nine out of ten executives surveyed reported challenges in 2024. At the same time, the analysis highlights gaps in deeper supply chain transparency and in the speed of response to disruptions.

This has practical consequences.

A company that focuses solely on optimizing inventory turnover may lose critical parts. A company that focuses solely on maximizing machine uptime may lose flexibility. A company that focuses solely on cost reduction may lose its ability to deliver.

Operational Excellence 2026 therefore requires a new balance between efficiency and resilience.

First, this involves a criticality-based buffer strategy. Not all inventory is good. Not all inventory is bad. What matters is the function it serves. A buffer must be justified, measured, and regularly reviewed.

Second, this requires realistic capacity planning. Many plans only appear flawless because they ignore real disruptions. Maintenance, setup time, training, sick leave, scrap, and priority changes must be factored into planning.

Third, this includes a standardized re-planning process. Companies should not wait until a disruption has already occurred to consider how to re-plan. Triggers, roles, escalation levels, and scenarios are needed.

Fourth, this includes data-driven transparency. Without reliable master data, up-to-date inventory levels, maintained delivery times, and clear capacity calendars, any planning remains fragile.

And yes: this also includes AI.

AI-supported planning can help make material availability, capacity bottlenecks, and scenarios visible more quickly. It can prepare alternatives, prioritize risks, and support decision-making processes. But AI is no substitute for leadership responsibility. The NIST AI Risk Management Framework makes it clear that AI applications must be managed in the context of their risks and trustworthiness.

For Hellmuth-Sander-Consulting, this development is central. HSC does not see itself as a standard consulting firm, but as a project stabilizer with leadership and lean DNA. Especially in critical infrastructure, supply chain, and transformation programs, what is needed is not abstract lean rhetoric, but robust implementation.

The work begins where complexity threatens execution: stabilizing processes, clarifying control, making bottlenecks visible, accelerating decisions, and embedding improvements sustainably.

Lean 2026 is therefore not a retreat from efficiency. It is a step toward intelligent efficiency.

Lean remains important. But lean without a safety net is not excellence. It is a risk.