Excessive use of AI tools can harm productivity, warns BCG study

Adding another artificial intelligence tool to your daily routine doesn’t necessarily mean you’ll work better. A study by the Boston Consulting Group (BCG), published in the Harvard Business Review in March 2026, found that perceived productivity increases with up to three tools but drops when professionals use four or more.

The research, conducted in partnership with the University of California, Riverside, surveyed 1,488 full-time employees from large companies in the United States.

Study findings

The authors coined the term AI brain fry to describe a mental fatigue caused by using or monitoring tools that exceed a person’s cognitive capacity. This is distinct from burnout, which is a chronic emotional exhaustion.

When moving from one to two tools, perceived productivity increases significantly. It peaks at three tools. From four tools onwards, performance declines, while mental tension continues to rise.

Among the AI users surveyed, 14% reported having experienced this condition. Those who intensively supervise AI tools reported 14% more mental effort, 12% more fatigue, and 19% more information overload. Affected individuals also reported 39% more serious errors.

Why supervision matters more than the number of tools

The strain comes less from the use of tools themselves and more from constant supervision. Every AI-generated response needs to be read, verified, and often corrected. With multiple tools, professionals switch between different interfaces and formats, which demands more attention and working memory.

A senior engineering manager interviewed in the study said he spent more time managing the tools than solving the actual problem.

Practical example

Imagine an analyst who uses one assistant to draft emails, another to summarize meetings, a third to create spreadsheets, and a fourth to research data. Throughout the day, he needs to verify four types of output, each with its own flaws. The time saved in production can be consumed by review.

How to reduce the overload

According to the researchers, using AI to replace routine and repetitive tasks can reduce the occurrence of this problem. They also argue that companies should proactively manage the negative effects without abandoning the adoption of the technology.

The results suggest that the optimal balance is up to three tools, each with a clear function, such as writing, data analysis, or meeting organization.

Limitations of the study

The data is self-reported, and the authors acknowledge that it remains unclear whether AI brain fry is a lasting phenomenon or an adaptation phase. The incidence varies by field: 26% in marketing and 6% in legal.

In another study involving nearly 12,000 workers across 14 countries, BCG found that more than 40% of regular AI users without management roles reported saving a full day of work or more per week. Both studies indicate that the benefits depend on how the technology is used.