I would assume that the CAT format is going to stay with us. I’d also assume that exam question will be constantly renewed, and that at another slower pace the CBK will change.
Feel free to share the exact tests and app you have(there are probably a few)I would not view any exam preparation materials as consumer durables, and would advise that you study from where you feel you are starting from. Anything from one to six months is probably the range of prep time I’d recommend. There are quite people that can basically walk in off the street and pass all the way to those that need to study comprehensively, but if it’s more than six months I’d say it’s dragging, and it’s not worth doing more that reading a book and perhaps a review course we’re really all the people I know required. For my own learning style I view test exams as wasted effort.
having spoken in the past I’d say your best starting point with ISC2 is to take the SSCP and use that as base to work off, you could add in some other baseline certifications and that will you in a place to start preparing for the CISSP exam in a couple of years.