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.