Lol, not even close. I'm sure that this is a common belief among arty-haters.

It's completely random and it seems that some days are more random than others. After some patches, I could swear that arty accuracy went to crap, but then was fixed days/weeks later. Having your shot land WAY outside the reticle after waiting 30+ seconds for reload and aiming is very frustrating. Personally, I think they should increase arty accuracy but decrease the damage (and put a cap on how many arty per game!).
[General arty tips you may already know]
Depending on the shape of your reticle and the underlying terrain of your target, it is often better to aim behind-ish of your target. Different arty's have different firing arcs, so this is different for each arty. If your reticle is a circle, you're dropping the shell from straight above, and you should generally aim more for the center of the target. If your reticle is long and stretched out, you're firing more at the side of the tank, and to avoid shooting into the ground you have to adapt by shooting more behind the target (i.e. almost shoot "over" him). After you get good with your specific arty and gun, don't let any single shot dramatically change how you shoot your next shot, unless that shot showed you something about the terrain that you didn't see before. It's pretty easy to change your target position only to realize that you had it right before. You don't often get more than 2 shots before you move on to another target.
I play about 5% of my time as arty (currently tier6 M12). It's my least favorite playstyle.