A few days ago I had 3 rolls of B&W. I processed 2 over the last 2 days, and I think I've finally corrected my issue with uneven development. For a long time I thought it might be bromide drag. I switched from stainless reels and tank to a Paterson tank, and the problem seemed to be less pronounced. I attributed it to better circulation through the plastic reel. But it didn't go away entirely. Finally, I've backed off the number of inversions-- from 5 every 60 seconds to 1 every 30 seconds. This roll seems to be free of uneven development (lined up with sprocket holes). So, the problem must have been surge effect rather than bromide drag.
The stainless reel must offer better circulation than plastic. Now I can go back to the stainless tank (which I always preferred over Paterson anyway). I just need to go easy on the agitation.