60-90 days is a good quarantine period for cresteds, although i lean toward 90 days if the source isn't extremely reliable (a.k.a. well known breeder). the biggest concern with cresteds is entamoeba invadens: http://www.ciliatus.com/content/inde...=42&Itemid=207. this can appear in seemingly healthy geckos when they are presented with the stress of a new environment (or any other stress) but may not show up for several weeks. it is highly contagious, and even if other geckos that come in contact with the sick gecko do not appear to get sick right away they will harbor the illness and it can appear later during a time of stress and prove fatal.

the fact that this person does fecals is good, but that alone should not be cause for shorter quarantine. imagine if a new gecko had entamoeba invadens but it was missed in the fecal. putting that gecko with her other geckos would then spread it to them and everything that the affected geckos came in contact with (food dishes, cage furniture, etc.). 2-3 weeks later the new gecko starts to show signs of illness and one can only hope that it will be caught in time, properly diagnosed, and treatment administered to the entire colony.

it is always better to be safe than sorry, and it's just silly to say that your QT practice is extreme based on the time you QT for. i'd prefer to QT for a decent amount of time rather than risk the health of my entire colony--seems like kind of a no-brainer.