What does it mean that every system has a bottleneck?

The slowest part of any system determines the speed of the whole system.

Example: You have a content creation pipeline: research, draft, edit, design graphics, publish. You spend a weekend building an elaborate Notion database that shaves fifteen minutes off your research step. Your output does not increase. It cannot increase, because the bottleneck was never research — it was the editing step where every draft sits for four days because you dread revising your own prose. You optimized the wrong station. The system's throughput is still governed by editing, which you never touched. Fifteen hours of infrastructure work produced exactly zero additional published pieces.

Try this: Pick one system you operate daily — your morning routine, your email processing workflow, your content pipeline, your exercise habit. Map every step as a sequential station. For each station, write down how long it actually takes (not how long it should take). Circle the longest station. That is your current bottleneck. Now ask: in the last month, which stations have I tried to improve? If the answer is anything other than the circled station, you have been optimizing in the wrong place.