Hi. I've been using Illustrator as my main art tool for most of twenty years.
1. Draw a circle. Give it a stroke in some color.
2. Open the Appearance palette.
3. Using the button at the bottom of the Appearance palette, add a new stroke. Make it another color.
4. Select this stroke and add effect>convert to shape>rectangle, relative sizing, add 0pt in X and Y.
5. Add effect>distort and transform>transform to the stroke. 70% in X and Y.
6. Open the Graphic Style palette and make a new style. Give it a name.
7. Visit the Appearance palette's menu and turn off "new objects have basic appearance".
8. Select the Graphic Style you made, draw some circles using it.
9. Turn off the Transform effect in the Appearance palette; hit 'redefine Graphic Style' and watch every circle change.
While your later examples like "make a little graph constrained to a shield" are more complex to make, there's still ways AI could help you do this stuff - you could maybe make a pattern brush with a circle for the end and corner pieces, and empty space for the main body, pile that on top of a plain stroke, and quickly drag some points around until you had a shape you like.
Eventually your examples get out of the territory of things I'd consider sane to do automatically in the tools AI has. But it can do more than you think.
okay enough procrastinating back to drawing my crazy comic in AI :)