From an (unconfirmed) study attributed to the US army Corps of Engineers :

« every time you double your workforce, you decrease your productivity by 20% »

Sayz (in the video below) Essential Craftsman, who also introduced me to the concept of « Shadetree mechanic ».

Study is most probably: U.S. Army Corps of Engineers – Modification Evaluation Impact Guide COE EP 415-1-3 (latest edition: July 1, 1979). Pdf of chapter 4 found online here. According to this 2013 study (pp 11-12), « the 1979 U.S. Army Corps of Engineers “Modification Impact Analysis Guide” (…) is still in use even though it has been formally withdrawn from publication ».

Ours des Pyrénées


(Source La république de Pyrénées – Pyrénées-Atlantiques : la carte des 100 communes opposées à l’arrivée d’ourses)