A really enlightening article: it threw light on what was a mysterious theme for me. I'd offer a suggestion, for the 4th code snippet, which bit me when I tried out with use strict. If we run it like this:

use strict;
use warnings;

package Szyewicki;

our ($Robert);
$Robert = "the boss";

package PoolHall;

our ($Robert);
$Robert = "the darts expert";

package Szyewicki;

print "Here at work, 'Robert' is $Robert, but over at the pool hall, '
+Robert' is $PoolHall::Robert\n";
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The result, which puzzled me at first, will be:

Here at work, 'Robert' is the darts expert, but over at the pool hall,
+ 'Robert' is the darts expert
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It took me quite a while to decypher why: the lexical scope of the 2nd our, under package PoolHall, is the file, so, when we switch to package Szyewicki, it's still in effect, making $Robert a lexical alias to package variable $Szyewicki::Robert. To work as expected and intended, the code must be:

use strict;
use warnings;

package Szyewicki;

our ($Robert);
$Robert = "the boss";

package PoolHall;

our ($Robert);
$Robert = "the darts expert";

package Szyewicki;

our ($Robert);
print "Here at work, 'Robert' is $Robert, but over at the pool hall, '
+Robert' is $PoolHall::Robert\n";
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The 3rd our alias $Robert to $Szyewicki::Robert.