IME the way you store and dose kalk can make a big difference. My dosing solution is in an almost air tight container, with a styrofoam float. If you can keep your kalk solution at a high pH it takes much less of it to get the job done. I still have to run an ATO on my tanks in conjunction with the kalk dosing.
There are many variables with kalk that will lower the pH of the solution and not give you the desired results. It does work, but it is a bit tedious. I can see why people would want to do other things.