Which factor is not essential to consider when deciding to join a coalition?

When considering whether potential coalition partners have experience working together in another coalition, it may be informative but is not an essential factor for deciding to join a coalition. The primary considerations usually focus on the mutual benefits of pooling resources, the alignment of common interests among members, and the external conditions that may impact the coalition's effectiveness.

These other factors are crucial: pooling resources can enhance individual and collective efficiency, shared common interests are vital for a cohesive and productive collaboration, and favorable social and political conditions can facilitate the formation and success of a coalition. Therefore, while having a history of partnership might provide some advantages, it is not a fundamental requirement to determine the viability or value of joining a coalition. This is why the answer regarding prior collaboration stands out as not essential in comparison to the other considerations.