Your statement that the first few % is - by far - the most significant effect on engine life
Look at that presentation again, the statement was that the first few % is by far the most significant.... Look at slide 8, you will see that the savings become horizontal as the thrust reduction is increased.
Also if you look at slide 12, a 5% thrust reduction will give you a $22,000 saving, whereas a 20% thrust reduction will not give you $88,000 of savings, so the first % is more significant......
Rolls once told us that a .01 EPR reduction would result in a 12% increase in blade life with the associated savings, however NONE of the engine manufacturers can provide us with proper and justifiable savings associated with operating with deep derates.... ie, what is the advantage of trying to average 50% reduction rather than 40%.
Mutt