How can I increase varying stroke thickness throughout a project?

Am I missing something? I get precisely the same results that Mike does just by selecting the whole path and going to the Control panel, Properties panel, or Stroke panel (all of which show the largest stroke value of the path) and increasing or decreasing that value by the desired amount. Other values are adjusted by the same percentage.

Peter

I very simple way is to click with scale tool and let go to get this menu. Then scale for example 200% with scale stroke, then again at 50% with scale stroke off, to increases seledted stroke thickness 200%.

I think I have seen scripts for that, but can't find them right now. What you could do is first scale up the complete object while scaling the stroke widths and then scaling down again, not scaling the stroke width. Or the other way round depending on whether you need to make the strokes thicker or thinner.

Edit: it's not a script, but a plugin: ToolShed: https://rj-graffix.com/downloads/plugins/#toolshed

I think what you could try is to save the stroke as a graphic style from the prior projects, then apply it to this new animal project.