How many AI tools is too many?
BCG/HBR reported that productivity gains from AI tools tended to peak around 2 tools, with diminishing returns beyond 3. The likely issue is cognitive overhead: remembering each tool's capabilities, switching contexts, and reconciling different outputs can start to outweigh the benefits.
One mechanism behind this threshold is attention residue, documented by Leroy (2009). Each time you switch from one AI tool to another, part of your working memory may remain occupied by the previous task. This is why BrainShield treats tool diversity as one behavioral signal in its scoring approach.
Source: BCG/Harvard Business Review, March 2026; Leroy 2009
Take the Brain Fry Score quiz