I was lucky! With holiday time I was able to spend some time (toooooo mmuuuccchhh) playing.  I committed one spyglass a day from early in the quest, and some fuel to speed up some flights.  With T/props and jets the flight times are quick.  There was a noticable difference between no SG and using SG.
I was also luck that I only had a few days of the higher fuel cost.
	
			
			I was also luck that I only had a few days of the higher fuel cost.