Jack,
When you say you are using flat and clean stones I assume you mean that they are freshly lapped?
When you start with a freshly lapped hone the surface will microscopically look like a furrowed field. A few passes later you have worn down the high area between the furrows leaving a much flatter and smoother feeling hone.
A freshly lapped hone cuts relatively fast, but what you feel is probably more the hones surface changing, but the bevel has also gotten smoother.
This smoother feeling should not be used as the solo indication that it is time to move to the next finer hone.
New razors or any razor that has a very narrow bevel will naturally take much less honing than blades with a very wide bevel.
Some of those large antique wedges can take a lot of passes before they are ready for the next hone.
I have the luxury of a fairly good microscope that helps me determine when the bevel is ready for a finer grit hone.