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

Like June, I make all embellishments like sugar flowers ahead of time.
I use rich mudcake type cakes as a base, generally… I like how they stay moist… particularly coconut or citrus flavours. For those flavours, I am happy to make them a couple of days in advance, it gives me more time to work on them. (The cost is much higher, but I find it worth it.)
As someone that has worked in many commercial businesses, with a high proportion of orders for Saturday pick-up….I can tell you, you would be surprised at the number of those orders that were actually baked mid-week.
Steer away from recipes that are notably “not fresh” after a day or two… like a buttercake, unless you are decorating closer to completion date.