re: How can I do more then one cake a week?

Get creative with your flavours… having moist fillings can help too… note the amount of buttercream in my example…
This cake is alternate layers of red and yellow velvet cake. Each layer separated by hazelnut meringue, dark chocolate ganache and vanilla bean buttercream.
Note: if you create a little wall with your firm ganache, to hold the buttercream, you will be able to maintain a straight edge on your finished cake… as long as it is not subject to temperatures that will soften your ganache.
(PS, I don’t add eggwhite to my buttercream… I guess it is more like a mock cream… for longer shelf life. Maybe others can advise different?)