I think it depends; for this module I would do this since it returns the reference if successful.

local $@;
my $book = eval {
  Spreadsheet::Read->new($file);
};
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or

local $@;
my $book;
my $ok = eval {
  $book = Spreadsheet::Read->new($file);
  1;
};
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The second example seems like "more work" to handle the error and is a lot messier. So in this case adding the "1" is superfulous since the called sub actually returns something (or doesn't).

A case where I'd use 1; with an or undef thrown in:

local $@;
my $ok = eval {
  doSomethingButDontWantReturnValButCouldDie() or undef;
  1;
};
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I think ultimately, the answer is like I stated above, it depends - on what you're doing and expecting; and how you tend to check for/handle exceptions.

I've also done this; but usually it's a game time decision for me.

local $@;
my $ok = eval {
  doSomethingButDontWantReturnValButCouldDie();
  1;
} or undef;
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