To adequately cool the electrodes we need to minimize their time at high temperatures so we need a lot of water flow. RWMA recommends 1.5 gallons/minute at the coldest temperature water available. Any compromise does not mean you will produce discrepant welds. It only means you will not produce as many good welds before dressing of the electrodes is required. This means down time in your production schedule which means fewer parts out the door each day. The recommended water flow rate is 1.5 gallons of water/minute per electrode. You can successfully produce good welds at 1.0 gal/min and 0.5 gal/min.
The photo below shows three standard full size RWMA A nose electrodes. Each made 2000 good spot welds on bare low carbon steel using the same welding schedule. The variable was water flow.
The left electrode had the recommended 1.5 gal/min flow and shows virtually no wear and could weld more parts without any face dressing. The middle electrode operated with 1 gal/min water flow and you can see some black heat effect and slight mushrooming on the face. You might touch this up before you started another part run. The far right part was tested with 0.5 gal/min and definitely shows heat effected area and definite mushrooming and is ready for the face to be dressed before proceeding to weld more parts.
The point is all of the flow rates are acceptable but the higher flow rate will produce more good parts before maintenance is required.
Refeerence: RWMA - Resistance Welding Manual