You have an insane amount of control of the FP that you use while crafting.
Crafts on earlier tiers skew lower, you can hold off on doing the T5 craft to hope to critically succeed it up, you can use despair glyphs instead of runes of removal, exalted and high tier rares drop with much higher base FP.
There are so many helping systems rewarding people who understand and use the crafting system that by endgame a completed craft can have upwards of 30+ FP remaining.