Is there much-if any difference in taste if a cake is 1 day old or 4 days old?  I baked and froze my cakes last night, ganached them tonight, and plan on adding the fondant tomorrow--but cake isn't due until the day after that---making the cake over 4 days old.....just curious if there is any distinctive notice??

Apparently Madeira tastes better after a couple of days. I often freeze my cakes and I think it retains the moisture better and helps it to last longer.

Many decorators say you can allow yourself a week to bake and decorate and a week to eat (although I would say during the first week is preferable!)

Thanks!  I myself have never noticed a difference in taste but wasnt sure there was a huge difference.  I am assuming as it sits it drys out but with the ganache and Fondant it should retain most of its moisture longer. 

I personally don't notice much difference but......the drawback of making a cake 4 or more days ahead is  that the customer won't have much, if any, time to use up any leftovers.  Also, depending on how hot it is and how it is stored there is a danger of it getting moldy &/or sour.

Depends on the cake you use, I do mudcake and they need to be at least three to four days old before you even touch them. They are crumbly and dry if you eat them before that. I bake anywhere from Sunday to Tuesday for a Friday or Saturday. My customers still have at least two weeks after that to eat their leftovers ( If they last that long ) 

Heavy dense cakes, like mud cakes, will keep much longer than will light dryer cakes.  Each situation will depend on the type of cake and the atmospheric conditions at the time.