did you eat a 120 skill scroll already? If not i suggest you do....i always find my gains better when i max the skill cap...
Specifically...
The gain window's top end gets expanded on a 1 for 1 percentage basis when you use a PS, for both tailor and smith training.
Examples:
No scroll: You stop gaining on an item when your unmodified chance of success is 100%.
105 PS used: You stop gaining on an item when your unmodified chance (theoretical) reaches 105%. As the DISPLAYED skill stops at 100%, that factors out to be 2.5 skill points past where it hit 100% (as the skills advance 0.2% per 0.1 skill gained).
110 PS used: Gain until theoretical 110% success (5.0 points past where item hit 100%)
115 PS used: Gain until theoretical 115% success (7.5 points past where item hit 100%)
120 PS used: Gain until theoretical 120% success (10.0 points past where item hit 100%)
To an extent, this is true for most skills with PS (not just crafting), but some of the skills advance at a 5/2 ratio instead of 2/1 (and some are even more bizarre, as the ratio is 10/7 for gaming imbuing via unraveling, with the total intensity of the item unraveled being divided somehow to get to the target number, instead of a "success" chance)