Hi 

Can you tell me what thickness you prefer of ganache under fondant 

Would 1/4 inch under fondant and 1/2 inch with no fondant be the right sort of balance?

AI probably use 3-5mm of ganache under fondant - 1/8-1/5 inch or thereabouts. I don't sell naked ganache cakes, if I have a dessert cake at home with a poured ganache coating, it would only be about 3mm too. Thicker is too much, too sweet/rich and way too expensive!

AI use exactly what you said 1/4 inch with fondant and 1/2 without.

AI use 1/16" fondant and 3/16" - 1/4" ganache. I like having sharp edges so I need the fondant to be thin. Plus, thinner fondant is way easier to cut and people are more likely to eat it.