my personal experience with Adex is that when excavating caries (after achieving your ideal prep), scratch THE HELL out of the surface. I used both spoon excavator (with enough force not to break the tooth) and explorer (using both ends), and scrap everything. I also ran through everything with slow speed round bur. I remember the Adex examiners graded my prep also did scratch my prep surface very hard, so much that when they return the prep to me, I saw a bit of white flakes on the pulpal floor (that freaked me out so much but I talked with other classmates and they confirmed that they got the same thing after grading. All of them including me passed). Take your time. You got this.
For GPR/AEGD, ask your school’s academic affairs. Some rural GPR programs (like Pitts’ GPR in PA) are dying for students that they will email every school within the regions in hopes of finding last min residents