[50CNT]

I like to think of blank pages as mini whiteboards. With a multifunction copier i can print out lined, grid paper or specialty layouts and whip it through the scanner once im done with it keeping a digital copy. 3USD buys me 500 pages, and with a laser printer [250USD], toner refill kit, etc. that comes out to less than a cent a page, or 3 cents if I amortize the printer over 10k pages (assuming it breaks once it hits its one month maximum duty cycle, which is stupid conservative).

That plus a nice fountain pen [Lamy Safari 18.7USD], ink [J. Herbin Perle Noir 7.2USD/30ml], mechanical pencil [Lamy Safari 12USD], pencil leads [Uni Nano Dia 0.9USD/20leads], technical pen [Rotring Isograph 16.3USD], and I've got a nice little setup.

[k_sze]

“I like to think of blank pages as mini whiteboards.”

This. I never enjoyed drawing diagrams in Inkscape, though my boss swears by it.

I’d much rather draw with pens on paper and then digitise by scanning.

[50CNT]

I could see your bosses workflow working as long as he has a library of common elements. For graphs I tend to use yED, which is nice. You know how LaTeX has the mantra that you input the data, and it worries about the layout for you? yED is similar, you add nodes, connect them, and then you chose from one of two dozen layouting algorithms, like "hierarchical", "swimlane", or even "family tree".