In other words, spend several days or weeks to do what you could have done in 4-6 hours using the link that elspeth cited,
If don't count time spent for collecting loot my method is only 1.5 times slower.
But, you HAVE to count that time - sorry. It would be like saying you had more time at home by working a 6-hour job that you drove 4 hours each way to get to and from, instead of an 8-hour job you drove 5 minutes to get to.
and it only is an option if you have a character that can fight monsters with spells or weapons.
But your method works only if you have a character that can fight monsters with spells or weapons (to earn gold) AND a crafter (or a house - so you can buy and store needed amount of jingasas).
Buy and store jingasas? WHISKEY TANGO FOXTROT?????
The method was MAKING Jingasas EXCEPTIONAL QUALITY, AS NEEDED. Even if you had someone else making them for you, you only need about 40-60 an hour, and it only takes about what your bank box can hold to go from 100 to 120 ( or 2-3 characters with half-full bank boxes, depending on how many storage expansions you have). The only place this would be an issue is on SP & Mugen with someone that plays only one account. And, you're more likely to find a winning lottery ticket on the sidewalk than one of those.
As for your PS, it's obvious you don't care about sticking to facts.
1-2. No one ever said you couldn't - only that it's slower.
3. That's still longer than the Jingasa method (where when I tested it, I had constant interruptions in RL, not the least of which was the fact that I started my training from 0 with less than 5,000 residue).
4. The 20,000 was a carry-over from the previous versions (where you had to train up from 25 imbuing, as that's where unraveling stopped), was at best a rough estimate even then, and didn't include the residue you got back from unraveling. I just noticed that, and fixed it - but if you'd actually paid attention to the numbers in the examples, you'd have noticed the discrepancy.
The jingasa method, if every other imbue failed, still would be less than 10,000 residue (700 per 20 jingasa at the TOP end (90 Luck, 13 RPD, 3 LRC)) with about 120-200 jingasa needed to go from GM to 120, and probably closer to 7,000 once you factored in unraveling what you made. It only took me 55 Jingasa to go from 117.6 to 120, and that's during the slowest gain period (and my success chance below what the game claims is optimum because I decided to imbue 7% LRC instead of 3%)