Royce 1970's argument is simple and presented linearly, which The Royce70 Diagrams do not convey.
It goes like this:
* There’s a big risk with the simple waterfall process. To minimize risk, do five things.
* First, add a Preliminary Program Design phase before Analysis. Perform these five tasks in that phase.
* Next, really lean in on documentation: write it and use it meticulously throughout the project.
* Next, spend around a fourth of your time making a working prototype.
* Next, take the planning and execution of testing more seriously, especially the following four aspects, which he then lists.
* Finally, get customer signoff after the preliminary program design, the individual program designs, and for final acceptance.
The supporting details are also presented in a linear fashion. They’re not wildly memorable, but neither is their representation in the figures. In either case, the reader who wants to put Royce’s paper to use is going to have to reread the details anyway.