Debate continues over how to assess Apple chief executive Tim Cook, with the argument that his contribution should be measured differently from that of Steve Jobs, the emblem of product innovation.

Supply chains are at the centre of the case. As chief operating officer, Cook redesigned component procurement and inventory management, reportedly cutting inventory turnover times dramatically.

Cutting inventory is not merely cost saving. Because component prices for electronics fall over time, keeping stock brief improves the cost structure itself.

That structure meshes directly with the component industries of Taiwan, China and Korea. Organising the capacity of Asian manufacturing clusters at scale is judged to be a substantive basis of Apple's competitiveness.

Expansion of services is also cited. Broadening revenue from hardware sales into subscriptions, payments and an app ecosystem happened under Cook.

Counterarguments exist. Critics note the absence of new product categories on the scale of the Jobs era, while friction with regulators and disputes over market power grew over the same period.

Judgements about management are hard to separate from the conditions of a period. Founder-style innovation and operational scaling are capabilities demanded in different phases, and generalising about which is superior is difficult.