The little nobs do control the flow and pressure to individual slides. It can be adjusted to create flow control and controling a specific slide.
For example if the bedroom slide is restricted enough the kitchen slide may open first before the bedroom one. But due to manual setting its a trial and error setup that might not realy do the required slide arrangement.
I have installed quick opening ball valves and just choose the slide action while the wife opens the slides on the insides in the order I move my sellection valves. I do prefer my system to the standard system Heartland and all SOB's do have been using. I can easily select one slide to 4 slide in the swing of a few handles.