Implicit quotas are preferable; if it really matters someone can ignore them. People try strategies of "we'll force the situation to be broken and then they'll

Implicit quotas are preferable; if it really matters someone can ignore them. People try strategies of "we'll force the situation to be broken and then they'll have to fix it!" every so often in politics. It often doesn't work with terrible consequences. People lack the imagination to look at a bad situation and easily come to a consensus about how to improve it. It is much better to enforce things by social expectation. Then enforcement measures can be changed piecemeal.