That's three answers with a wide range. The ratio of liquid to eggs for each of the above answers is as follows:
foodnfoto => 2.4 [48 oz liquid:20 oz eggs]
chiffonade => 3.2 [16 oz liquid:5 oz eggs]
Svadhisthana => 3.7 [6.3 oz liquid:1.7 oz eggs]
I suspect that the custard holding the quiche together becomes lighter as the liquid to egg ratio increases. In looking through some of my recipes that involve custards, I find ratios similar to the above. But here's recipe for quiche aux asperges vertes et au parmesan
that has a ratio of 1:1 -- and it still works.