Say you are doing a cake with fruit filling (non perishable). Do you put filling on top of the buttercream iced cake (bottom layer) before putting on the top layer or do you just put the filling on top of the plain cake (bottom layer), then put on the top layer?? Hope I did not confuse you...
Well, all my cakes are 4 layers (2 layers torted) and I generally prefer to put fruit filling directly on the raw torted cake. I like how it soaks into the cake a bit and makes for a more gradual transition between the textures.
The exception to that is my pomegranate molasses filling which soaks in wayyyyy too much. I put down a thin layer of buttercream on both raw sides and dam it up good for that one.