I haven't tried this app - and probably won't. The big red flag for me was 'weekly dose.' This is a concept that's a bit scary to me. I don't know if it's giving you the same dose daily, or extra half doses on certain days, just to hit weekly numbers (for example 7.5 mg Monday, Wednesday, Friday and 5 mg the other days. This may give you a good weekly dose, but it will skew test results depending on which day you test.
My 'application' is a simple Excel spreadsheet -- it records date of test, daily dosage (yes, most weekly doses can be broken into standard daily doses), time of test (although this may not be significant), INR, PT (although this varies from one batch of strips to the next, but can usually be trusted), and a field for comments. I've been keeping a record since I first started self testing in 2009. I've used a variety of meters through the years, and I still record which meter I've used (I currently have an XS and an XS Pro and occasionally switch between them).
If necessary, I make small dosing changes. If I think it's necessary, I can test three days after an event that may impact INR (starting an antibiotic, for example). This is pretty much all I need.
I have a seven day pill box and load it on Sundays. I take my warfarin at bedtime. I rarely need a reminder to take my pills.
Although I'm not running graphics of dosing vs INR, or stuff like that (and these may not tell me much), and I don't get whizbang graphics from a phone app, my simple system has worked for me.