Key Points

Bryan Cantrill argues that LLMs inherently “lack the virtue of laziness,” because producing more work costs them little while they can pile onto complex, messy system layers.
He warns that unchecked LLM usage can make systems grow larger rather than better, driven by vanity metrics and increased complexity at the expense of what matters.
The quote contrasts machine behavior with human finite time, suggesting that human constraints push engineers toward crisp abstractions and simpler designs.
Overall, the passage frames LLM deployment as a design/architecture challenge: humans must deliberately manage complexity and “garbage layercake” risk rather than rely on the model to optimize for maintainability.
The post is presented as a curated quotation rather than a new announcement, emphasizing principles for building and governing LLM-based systems.

Simon Willison’s Weblog

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13th April 2026

The problem is that LLMs inherently lack the virtue of laziness. Work costs nothing to an LLM. LLMs do not feel a need to optimize for their own (or anyone's) future time, and will happily dump more and more onto a layercake of garbage. Left unchecked, LLMs will make systems larger, not better — appealing to perverse vanity metrics, perhaps, but at the cost of everything that matters.

As such, LLMs highlight how essential our human laziness is: our finite time forces us to develop crisp abstractions in part because we don't want to waste our (human!) time on the consequences of clunky ones.

— Bryan Cantrill, The peril of laziness lost

Posted 13th April 2026 at 2:44 am