There's a HUGE difference between "worrying" about whether or not there is a difference in testlet difficulty and "noticing" whether or not there is a difference in testlet difficulty.
It takes no effort whatsoever to notice whether or not your teslets are getting harder. And to say "don't worry about it" is pretty worthless advice IMO because it is going to be in the back of your mind no matter what. You're going to notice regardless of whether you go in and say "I'm not going to pay any attention to teslet difficulty" or not.
Besides, it's not like your mentality is going to change regardless of what you notice. If you notice it getting tougher, you're not going to say "well I killed that first part, now I can slack off on these next 2", just as you're not going to say "man this teslet isn't any harder, I must have sucked on the first part, might as well give up now". Regardless of what happens, you're going to try your best to get each question right.
So to me, thinking about your teslet difficulty is not a "waste of time and energy" seeing as it requires literally 0 time and/or energy to notice if your tests are getting tougher or not.
FAR: 81 (1/20) AUD: 88 (2/27) REG: 91 (4/19) BEC: 75 (5/20)