This is how it started back in 2001 when I was a typesetter for a small DTP department oin a big company from Romania. I have written thousands of equations, from simple 1st degree to integrals and sums in the equations' editor integrated in Adobe FrameMaker. I was also working on hundreds of graphics created in Adobe Illustrator, from simple segments to second degree functions. These all happened before Adobe InDesign became popular.
Inputs for these layouts are usually Word documents or LaTeX files. The outputs are always in Adobe InDesign with equations in MathType and charts in Adobe Illustrator.