I agree with bellaluna. Me too has answered yes without dropping a LoE and has been requested to upload a schedule A a couple of weeks ago. So if you have answered yes to one of the statutory questions, it is better to explain it from the beginning.
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Schedule A is also requested systematically to all PNP. So if you are PNP it is better that you upload it with your documents from the very beginning.
I don't think EVERYBODY will get the request. Maybe if you filled out the personal history incorrectly (gaps), or you said yes to any of the statutory questions, etc.