This perk increases the training level of the role and non-role-specific skills of the entire crew by 5. It does not affect role-specific skills and perks (in-game description is incorrect). There is no benefit whatsoever if any of the crew do not have this trained to 100%. The perk stays in effect if a crew member is knocked out during battle. The perk is cumulative with Improved Ventilation and skill boosting consumables.
Whereas the in-game claims the benefit is lost if any crew member is knocked out. The wiki even reports that the in-game is incorrect. I don't know who to believe, and I would like to know before spending hard earned XP on the skill. Did the same people who made the game make the wiki? If so, then why the contradiction?