I was kidding about the weight and run time. Who will care about 0.5 second and 0.05 g ? Not me. It's my false not to make it more obvious (about being jokeing) and forgot to put some smilely faces
However if you connect 2 LED in parallel they will surely consume more enegy because you also lost the power in resistor too. You forgot about it in your first paragraph but mentioned about it in your second paragraph.
The correct calculation are:
1 LED+R consume power (P=VI) = (3.6+5.4)*0.02=0.18W
2 LED+R consume 2 times power of 1 LED+R = 0.36W
* 5.4V is voltage drop in resistor
P=VI= (3.6+3.6+1.8)*0.2 = 0.18W
* 1.8V is voltage drop in resistor
It's obvious that connecting them in parallel will consume more energy because of the extra energy wasted in the current limiting resister. That right?
About the runtime. I assume that mod motor will consume 30A = 9*30=270W so the extra energy 0.18W energy wasted is 100*0.18/270 = 0.067% and 0.067% of 300 seconds is a whooping 0.2 seconds!! That's just a roughtly estimate runtime to be used in my failed joke. Please don't be serious about that.
You're correct about the LED damage issue but I never seen an LED that damage in correctly designed circuit before.
Next time please being more careful about the word "rubbish"