When fusing, I use a slightly different strategy.
2x good for greats
2x great for flawless
CF fusions for Epic
4F for Epic (when appropriate commons not available)
3E for Legendary
3L for Mythical
When I have similar level items, I'll mix different items but keeping to the above formulas for reduced fusing times.
While it might take longer to fuse 2x greats for a flawless item than doing good/great combinations, you are guaranteed a flawless with a 75% chance.
I did my own figures when I started and I was getting very few flawless on good/great fusions while averaging around 92% success rate using 2x great.
As for other chances, I did 4 fusions overnight where each contained 3x epic Evil Seals at 45% chance of success. Woke up the following morning and collected 4x Legendary Evil Seals. I was hoping for 2 and expecting to see only 1. Mythical fusions are worse as it takes a lot longer to gather enough legendaries for 4 fusions so you normally run the one fusion you have enough for with the inevitable failure...
While the chances of you getting the results you have are very low, it is not an impossibility, just unlikely. It's the same with winning the lottery or having an item actually break in a team with high levels of support - it WILL happen eventually if you participate for long enough...
Mayor of Elysìum (rank 191 Nw)
Lvl 51, 122.1G Nw, 451/559 BPs mastered.
All wood/leather/iron BPs.
17/36 Gold. 3/44 Primal.