Yep, I test at least a couple times a week. If I had a Checker I would test far less frequently. There's just no good reason to have anything more complicated than a single reagent titration kit, anything else is just overcomplicating matters. I also suggest API for calcium. However, the checker is great for PO4.
Lastly, for anyone that uses Elos, or is thinking about getting an Elos KH kit, I think you'll find the results and test method remarkably similar, yet considerably more expensive.