Sorry it was a joke

Yes of course you are right, it took me more than 30 minutes. But I was talking about you, not me - and why wouldn't you do Something like that in 30 minutes ? Or 1 hour
OK, I understand what you want to do - some call it stamping.
Each mountain has a very similar shape (but not identical) and different sizes (from small to big) and you draw them by hand one behind the other starting with the small ones in front then increasing the size and then going again down like if you were "stamping".
Some people even create brushes with different mountain shapes and then literally stamp them.
Once the stamping done you do just some postprocessing (add shadows, enhance some details and eventually color the thing). The key is to use relatively few lines for the "stamps" so that drawing them becomes a routine.
The advantage of this method is that it is very fast and can be standardised. As you will use at maximum a dozen of different shapes (very simple for small mountains at the edges of the range and more elaborated for bigger mountains in the middle) , once you did this kind of mountains 5 or 6 times, it will become an automatism.
Disadvantage is that even if the individual shapes will vary, your mountain ranges will look basically the same on every map.
Perhaps for training the stamping method is good - it's your choice and your map.