My avalons don't seem very consistent. I'm running 11 A6's and my shift graph has huge spikes of high and low and inconsistency. My S7's are almost dead on though. I've even ran the A6's through 3 separate controllers to see if that would help and nada. Maybe that's how they are supposed to run, I don't know.
https://imgur.com/MD1CFHYMy 741's are very consistent. However, once enough time elapses the graphs changes its Y value increments to much smaller units, therefore you'll see what look like larger variations of hash rate although it is fluctuating fractions of a GHS.
Have you looked at the image of my shift graph? I was wondering if it was normal, but you can see my S7's at the bottom are very consistent as well.