Well, you answer your own question. "When can you be ABSOLUTELY sure" ..... Its when visa is stamped on your passport and its in your hands

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Under new rules for FSW..... no interviews as general, unless its needed in case IO is not sure about any information..... otherwise you can say No chances. If an applicant is not eligible..... its gonna refuse even on 66 points... no matter funds and bla bla. So, Interview is not much associated with funds or Job experience.