It is very easy to set a conductivity controller so it is on all the time. Flow controls piddle a little bit of water into a rinse tank continuously. They are not meant to be turned on and off. Unless you do every line in a shop, what happens is that any lines still open flow at full bore all the time, and you see very little change in water flow. One way to look at it is if you are using 30 gpm and you put 15 flow restrictors at 2 gpm on 15 rinses, you still flow 30 gpm.
Timers determine water flow based on line size, water pressure,and time.
Once you put timers on, the first thing you notice is that your water pressure returns to normal. Timers can be activated in many ways so that the flow can be configured for a predetermined rinsing program. For example, a pushbutton on the previous tank is pressed to activate the next rinse so that when the rack arrives, the water is rising and overflowing the tank. This will reduce the dragout remaining in the rinse tank and reduce the overall rinse water required to maintain process quality. The actual amount of water flowing through a tank can be determined and dragout rates and dilution ratios can be calculated and verified.