Calls for such research:
Pierce, J. R., & Aguinis, H. (2013). The too-much-of-a-good-thing effect in management. Journal of Management, 39(2), 313-338. doi: 10.1177/0149206311410060
Grant, A. M., & Schwartz, B. (2011). Too much of a good thing: The challenge and opportunity of the inverted U. Perspectives on Psychological Science, 6(1), 61-76. doi: 10.1177/1745691610393523