I assume you mean Jingasa helmets.
The method should be Craft about 20 Jingasa exceptionally (and only use exceptionals for the imbuing training), to get mage armor to raise the difficulty of later imbues. Use a low end Ancient Smith Hammer if necessary.
Imbue one property onto each jingasa ONCE that gets it up near your range for optimum skill gain (or two mid range properties to get to a similar level)
THEN
Imbue a different property that takes 1 residue and 1 cheap gem on the item 19 times over and over, until you get the message that indicates you're unlikely to get further skill gains on it. Switch to the next Jingasa.
After doing this to all 20 Jingasa, unravel all 20, and make 20 new Jingasa - repeat the proces/
Crafting a single high cost property 20 times on one item is a bad thing. That might take 150 residue and 300 gems.
Doing the 1 big property once, and a tiny property 19 times takes about 25 residue and 50 gems. And, usually, only takes about 100-200 jingasa to get from GM-120. Much less if you have Scrolls of Alacrity to increase the gains to 0.2 to 0.5 per gain instead of 0.1 gains.