The ending is deserving an oscar at 2:15 - 2:20 Hahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahaha :)
ASTM D4541 pull-off test (for wood or steel substrates) and ASTM D7234 (concrete pull-off test) will always be more reliable. Cross-cut tests (tape adhesion) are just a simple checking test
Generally it depends on the test area and the number of panels you have. It's different to how you prepare panels in the laboratory, different to how you have to perform a test on an element whose surface is limited, e.g. on a construction site or on panels after SST. It also depends on whether you have a good result, an evidently bad result or a moderate failure of the cross-cuts. If the result is clearly bad (100% failure) or clearly good (0% failure), it is enough to do 2-3 repetitions. If you have an intermediate result, you should do 5-8, and sometimes even 10 repetitions for adequate repeatability and precision.