The big downside to using runic-made items to train is the fact that the properties are themselves random. This will change the amount you imbue from item to item, to get the same effect.
Not to mention that on many shards, DC & Shadow hammers have actually gone up in value considerably, as tools to make items to Imbue for actual use/sale. You could buy 1000 diamonds or 3000 amber for what you could sell 2-3 DC or Shadow Hammers for. So, any savings from using the runics is nullified by the loss of the value of the runics compared to the cheaper cost of the gems, in comparison.
The Jingasa method (which its original discover was actually doing on more difficult SE plate armor pieces, not realising the Jingasas also got mage armor) has the benefit of simplicity.
1. Make 20 exceptional Jingasa with an ASH +10
2. Imbue them all with the first property (luck). This way, you only have to use the imbue last property and retarget.
3. (if needed) Imbue them all with the second property (RPD) as high as you want/need to go to get the 3rd install at minimum cost as optimal. As #2, for using imbue last property.
4. Go to each, one at a time, and imbue the LRC at minimum cost (or close to it) 18 times successful. If the success chance starts slipping out of your optimum range, increase the LRC 1 step.
5. Unravel the entire bag, then Repeat, making sure to add or increase the RPD as needed to reduce the costs of the LRC imbues.
This requires no sorting of runic-crafted items, no mining or buying of colored ore, and is fairly easy to set aside and resume as time allows.
And, yes, the disco trick is useful, right up to 120 - you just got to make sure that the differing levels of disco one can find on satyrs won't put you overweight when you recall out to the forge. Note that Paragon Satyrs can drop you a lot lower than normals (like, about 8 skill points more)
Also, you DON'T want to use the queen's forge for any sort of training by unraveling - its bonus reduces your gain chance by increasing your success chance. You're better off using a home forge, or the 3rd public forge in Ter Mur (one of the outer buildings also has a soulforge, that doesn't have the bonuses of the Queen's forge or the one with the quest NPCs).