Large search parties are not always the best option, I have a 2 person party, one guy has 3 2 1, the other one 1 3 2, and they have 53% chance to go unnoticed, 85% to survive if spotted and 40% to find loot.
I also noticed that even if some people have the same stts, they add different percentages to search parties
When withdrawing: If you do not clock on Withdraw all, it can happen that the units just dissappear. Developers, PLEASE, for CHRISTS SAKE, answer one of my mails and fix the multitude of problems