Obvioulsy I don't drive the mileage that you do, but I can't imagine going through a gallon a day. Are you using WWF for other purposes? I really just spray the window to clean off drying road salt spray from other vehicles. The rain-x has little value here, it's advantage is allowing rain and snow to slide right off the windshield, making visibility better and reducing (or eliminating) use of the wipers under those conditions. I'm that car at higher speeds driving w/o the wipers on. It does fine when used to "clean" the windshield, but any spray can accomplish this.
I only pay $1.99 to $2.49 for Rain-X WWF at Walmart. If you wouldn't pay "whatever" it costs, than it seems you are wedded to Aquapel and aren't interested in a comparison. That's fine. I don't have allegience, and will be happy to try Aquapel and compare. There's no other way to really know what works (and what doesn't) and what I prefer. Same is true for tires and oils and everything else that people get attached to.
I followed the directions?

My bottle of Rain-X "original" is so old, it has a paper price tag on it! I use it once a year, once the temps have reached the warmth indicated on the box, and it gets shared by both our TDIs. It takes very little to wax the windshield, and I think I still have a quarter bottle remaining. I also have a bottle of Rain-X "anti-fog," but I found it doesn't have much impact on the interior. It works well for motorcycle faceshields, and crewman goggles/eyewear used in combat.
I previosuly used Rain-X original with other WWFs, but the wax only lasts half as long. Again, the blue stuff seems to eat away at it. Maybe Aquapel resists this since it's fluorinated, where as Rain-X is silicone based?
I agree on the Bosch Icons, but I'm still using the original VW wiper arm and blade, the OE with the wind-assist blade on the driver side. Why? Because I wanted to do my own comparison. I bought two passenger side Icons on sale, and each of our TDIs received them. Then, I put a new rubber insert on the driver side to have a level playing field. The Icons are nice, but a bit pricey for the performance compared to OE- and every day, with every wipe, I have a perfect side by side comparo going on.
For whatever reason, the Rain-X WWF allows the rubber inserts of both blades to last longer than any other WWF I've used. The cheap blue stuff seems to dry them out terribly quick, and they get stiff. I (used) to have to treat them with Aero303 to maintain the soft rubber. The cheap blue WWF (various brands) seems also to make the other rubber and plastic near the windshield dry out or fade, too. Maybe it has more alcohol in it? If I use blue WWF in a pinch, I find I'm out treating all the rubber and plastic with Aero303 after a few weeks.
I'm looking forward to the Aquapel comparison. It's fun to see how well things work, and how they compare amongst others. Even in the same line of products, some seem to work well, and others less so. I'm not a fan for Rain-X wiper blades, waxes, or other sprays, although I guess now they are all part of the Shell group, which makes many auto products (including Rotella T6, etc).