The number of 5–7 intense decisions is based on research in cognitive psychology, which shows that our decision-making resources (self-regulatory resources) are limited and quickly depleted when making difficult choices.
Roy Baumeister and Kathleen Vohs, in a series of studies (Journal of Personality and Social Psychology, 2008; Baumeister et al., 1998), demonstrated that each subsequent tough decision consumes part of our cognitive resources, and after around 5–7 such decisions, we begin to make choices that are increasingly impulsive and based on simplified patterns.
This phenomenon is known as ego depletion, which leads to a reduced ability to analyze details and a higher tendency to rely on simple indicators like price or availability.
Research by Sheena Iyengar and Mark Lepper (Columbia University, 2000) further showed that too many options lower satisfaction with the final decision and increase the risk of decision paralysis.
Levav et al. (PNAS, 2011) showed in a study of judges that after several rulings, there was a significant drop in the quality of subsequent judgments, as the cognitive system seeks to avoid further mental effort.
That’s why, in practice, it is recommended to analyze no more than 5–7 offers in a single decision-making session, as exceeding this number increases the risk of subjectivity, fatigue, and cognitive bias.
Harvard Business Review (e.g., Gino, 2016; Hemp, 2011) popularizes these mechanisms by reporting that managers, after several tough decisions, become less capable of objective analysis and more prone to automatic decision-making.