After they re-scaled the ENY system I had to cancel my sub for a short while and resubbed again. Ever since it's been almost impossible to make any respectable perks. I fly high ENY planes (ENY 30, etc) and land a number of kills per sortie, and still barely make 5-6 perks a run. Even with plenty of stick time it's very very hard to make perks, even if you win the glory of getting your name in lights. Now that my stick time is cut back significantly, it's flat-out impossible.
Just for example, the planes I like to fly include: 109F4, 109G6, C202, C205, Fw190As, all of which have a decent ENY for perk farming, but the results are the same: It's darned hard to make any perks!
Even WITH a 1.5 perk multiplier in the hangar and landing 4-5 kills in a C2, I still only make single digit perks! It's crazy! There's almost no reward for killing bombers, either. That's another matter altogether, I fear.