I wasn't concerned about the mold itself, but the 1st, 2nd, 3rd layer of soap after the 4th, 5th, 6th layer is poured. What will the new weight do to the soap already under it? What will the new heat do to the soap that's already started to heat up? She's adding more heat and insulation with each layer of soap that she pours. Not something that someone used to making small batches is prepared to deal with. Keep in mind she isn't talking about doing a layered soap, but layered batches of soap. Nothing like what Ophelia's soaper does at all.
I think sectioning off the length and width of the mold is the best option for how
@Kimberly Kavanaugh is used to making soap, don't worry about filling the mold to the top, just create sections sized for your regular batches. As
@dibbles said, there's no rule that the mold needs to be full. Just make sure that if you section things off, there are good supports for each section wall so that they don't move when pouring soap. You can remove the support when the soap is set. I have done this with my really long (24") tall and skinny mold when I only need to use half of it or other goofy length for an odd number of bars. (e.g. my 12" will give me 9 bars, and the 24" will give me 18 bars, but sometimes someone wants something like 13 bars, so I adjust the recipe for 13 bars and adjust the mold length with section walls and supports). I have also done this when I want to do (2) 12" batches, I just pour one on each side of the section wall.