Here’s a good news-bad news scenario, as a player gathered up a whole lot of Mythic uniques and runes to get a good Greater Affix (GA) roll on a 
Shroud of False Death. Except before they took the plunge and started crafting, an almost perfect one dropped the regular way!
Raphattack was gathering a whole lot of runes and potential Resplendent Sparks to mass-craft a whole lot of Shrouds. Even then they were well aware of the almost futile nature of it. They already had a regular Shroud, but were going to roll the dice on more than one Greater Affix. Fully expecting to make 20 or so Shrouds and have none of them be better than 1 GA, a miracle happened and a triple one dropped just out of the blue! Andariel was the generous boss that made it all happen.
We even got a breakdown of all the Mythics present in the bank tab, which was also changed to purple – which you clearly need when you have a full stash tab of Mythics).
- 6x Andy’s.
- 5x Shakos, zero cooldown reduction :(.
- 2x Heir of Perditions
- 2x Tyrael’s
- 2x Shroud
- 9x Shattered Vow
- 9x Nesekem, The Herald
- 11x Ring of Starless Skies, zero +core skills 🙁
- 4x Melted Heart
So if you were planning on crafting a whole lot of a specific Mythic, maybe do them one by one, and not 20 at a time and save yourself some materials!