Lenny RachitskyHost of Lenny's Podcast | Author of Lenny's Newsletter

The end of the 4-hour work block

20 Oct 2025 · 1 min

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0:39

A short spoken segment from Lenny Rachitsky arguing that work has shifted from long, uninterrupted four-hour blocks (which previously yielded two to three hours of deep work) to an interrupt-driven reality for coding and systems. He questions whether four-hour blocks remain useful and suggests shorter 45-minute blocks can be effective because machines/tools can help hand back context, reminders, and generated artifacts (like system diagrams) to restore flow.

Chapters

When we think about what it used to be like back in the olden days, three years ago, three and a half years ago, we could block off four hours of time and we could probably get two or three hours of really good work done. We were just focused, right? There were no interruptions. Now, the nature of writing code and systems itself is interrupt driven. You start something and then it interjects. And so how do we think about that? Does that mean that a four hour work block is still useful? Probably. But does that mean that now we can also make a 45 minute work block useful? Because getting into the flow is actually kind of handed off. The machine or the machine can help us get back into the flow by reminding us of context and generating diagrams of the system and all the things.