As a model designer you have to think about where you want to start.
This has an influence on the design of the parts, because it induces a certain order, like the design of the slots for example. So the epicenter is the Engine Chamber, for several reasons. You have to be aware about the sheer size of the LUT model. The square shown above has a side length of 17.5 cm, the entire cross just fits on an A3 sheet when placed diagonally. However, this means that the MLP must be cut into pieces if you want to keep the A3 format of the sheet (which is advisable for shipping reasons).
Splitting up the MLP parts carries the risk of the box warping during assembly, so the construction must anticipate and avoid possible sources of error as much as possible. The Engine Chamber as the center of MLP can still be constructed without splinted parts, and exact horizontal and vertical lines continue from there to the periphery.
The Engine Chamber has to be very stiff, especially since it also carries the weight of the Saturn, which is no problem with a paper Saturn, but which plays a role with the Revell - Saturn with its weight of 1.5 kg.