I'm getting what looks to me like uneven development on my 4x5 negatives. In case it wasn't visible in the scans, I drew roughly parallel lines on some of them. These are scanned contact prints. The other two looked okay. I use HP5 in HC-110B for 5 minutes. Am I agitating too much? not enough? Are the sheets hitting each other? Agitation was +/- 90 degrees from vertical, with rotation in the film plane, followed by tapping a tank corner on the counter. I was doing other things but roughly agitation every thirty seconds with fifteen continuous seconds at the end.