As water gets warmer in summer months it is less dense, more fluid, so the waste ratio goes down. As it cools off in winter months it becomes more dense so does not pass through the membrane as easily and the waste goes up. I either have one capillary tube flow restrictor I trim during the shoulder months when the water temp is around the middle or if the temp difference summer to winter is drastic as it is in some places then I recommend having two restrictors, one trimmed for winter and one for summer then change it out as the season changes. Takes a total of one minute if that, that is if you remember it. I tape the restrictor right to the membrane housing so it is in plain sight. You may need a different size restrictor to fit your conditions. Buckeye or Spectrapure could advise you on the correct one.
You are smart to stick close to 4:1 if you have hight TDS and hard water, your membrane and your wallet will than you. 3:1 is fine if you have soft water and lower than normal TDS.