No it's not. Crit rate isn't as low as everyone thinks it is, mines at 31%, so almost 1 in 3 attacks will proc 2 CPs. Not only that but OoC, at least for me, procs quiet a lot, and since i'm still into the habit of spamming shred to 4CP, it normally gets wasted on a shred anyway. Very very rarely do I not get to 4CP before PS runs out, and even in those rare cases which I don't, I still have NS to save my ass, which atm I consider a part of my opener, and an "Oh shit I messed my rotation" button. That or used for target switching which I don't really agree on.
Extending the duration of PS would just kill it. You also get the 6 second window. PS is 8 seconds. Granted you will be in a GCD the 1st second, so lets say you get 7 seconds of active time, which is more then enough imo, has been working out fine for me, never heard anyone else complain that PS is too short either.