A limitation of a heat map is that it can be challenging to differentiate between impact and likelihood as to which is more important. Heat maps visually represent risks based on their impact and likelihood, but they do not inherently provide a mechanism to weigh these factors against each other, which can make prioritizing risks difficult in some cases.
IIA References:
* The IIA's Practice Guide on Risk Assessment discusses the use of heat maps in visualizing risks but also highlights their limitations, particularly in how impact and likelihood are presented. While heat maps are useful for a high-level overview, they may not provide the nuanced understanding needed for decision-making when both factors are critical.