Since the ROC isn't changing by very much because of the iron tool, you can just continue doing the central stroke.
FWIW, you can go fast enough to work up a good sweat on this rough grinding and apply a fair bit of pressure at this time. Some people apply a hundred pounds or more when doing rough grinding like this on grinding machines and run the machine at a high speed to get the job done fast.
You do want to slow down at the end of the grinding to get a finer finish tho.