Allowing for little bit of “wiggle room” might seem frivolous, but it can have massive implications.
Slack, by Zvi Mowshowitz - https://thezvi.wordpress.com/2017/09/30/slack/
Some Consequences of Having Too Little (Shah, Mullainathan, & Shafir, 2012) - https://scholar.harvard.edu/files/sendhil/files/some_consequences_of_having_too_little.pdf
Scarcity: Why Having Too Little Means So Much, by Sendhil Mullainathan & Eldar Shafir - https://smile.amazon.com/Scarcity-Having-Little-Means-Much-ebook/dp/B00BMKOO6S/ref=sr_1_1?s=books&ie=UTF8&qid=1506174951&sr=1-1&keywords=scarcity
Made of Indestructium, TV Tropes (Warning: TV Tropes will ruin your life) - https://tvtropes.org/pmwiki/pmwiki.php/Main/MadeOfIndestructium
On the Psychology of Scarcity: When Reminders of Resource Scarcity Promote Selfish (and Generous) Behavior (Roux et al, 2015) - https://goo.gl/GM4yGT