Every piece of cannabis is different. So if you want do same test twice you have to you same piece of cannabis. Not bud from same plant, it can differ.
But i did some tests twice and the results was same.
PROS: you can do your analysis at home
CONS: it takes a while and some work to do it properly
i dont use fire to do "HOT" test and color spray. Instead i use laser thermometer and oven to decarboxylate cannabis and bath with color identificator.