I'm going off memory here, I almost never clean anything, there is a very slim chance I'm wrong and ours works as you say but I'm 99% sure I'm right. I'll check.
Assuming my memory is correct ( I feel it is): It depends on how it's setup. I have our siphon tee'd into the fresh water supply to the pump AFTER our bypass loop feeds back into the fresh supply line, and after a ball valve used as a flow restrictor. This means the pump is still drawing chemical when the regulator is in bypass mode due to the restrictor valve. The chemical will draw lighter in bypass mode but it still draws some, probably half. So 1gph in bypass and 2 gph when triggered.
When I had it setup to draw before the bypass loop it wouldn't be as consistent at low gph settings. I'm not sure why but it would work for awhile then drop to almost nothing after awhile, maybe if the wand wasn't being triggered for awhile, maybe switching tools with different flows, again I'm not sure.