re: How many Layers

Generally I make my cakes 4" high… baked in at least 2 layers, but depending on flavour, sometimes 3 or 4 layers.
For my 6" high cakes… at least 3 layers.
As a hobby baker, I do not have a lot of cake tins, so this is a consideration…
A 4" high cake with 4 layers… I generally bake in 2 tins, and cut to make 4… to save having to bake in 2 separate batches.