This leads me to believe that the farther you are from the hard cap (in this case, ten levels), the more often you get higher than 0.1 skillups.
I have only ever seen a 0.3 skill up when the gap was 8+ levels.
BTW at a 10 level gap it is impossible to get to less then 5.5
Skill Cap - Your skill - (Sum of "The Factors")=X
That is the largest factory you can gain.
I hope you were happy with the gains you got at 10 level gap. I would be happy with those results, for sure.
1st stack : 6x 0.1 skill up, 0 breaks, continuous synthing
2nd stack : 1x 0.1 skill up, 0 breaks, continuous synthing
0.7 up in 24 synths.
This would be just under the accepted average for post lvl 50 crafting.
The fact that it was .6 and .1 per stack is trivial, because even 24 synths is a small sample. As stated.
The problem... 1 level gap.
No matter how many negative effects you stack on, skill ups at 1 level gap as less then ideal.