I’d say evidence is that which provides support for the entirety of a claim, or part of that which provides support for an entire claim if you also have evidence from other experiments. I do feel that there is an amount of observations that’s sufficient to make a universal claim; I don’t have any problem with someone suggesting multiple, consistent observations are evidence for multiple consistent occurrences. And actually observing all cases would be evidence for all cases.
That 99 ravens may be black means nothing as to whether the 100th is, and is no more evidence that they all will be than if you had 98 or even just 1 observation. An observation must back up the entire premise to be considered evidence for that premise.