In the  qr/(?:(simple).*?)+/ regex,  .*? is satisfied with nothing, so it's happy. Then  (?:pattern)+ is satisfied with a single  'simple'. If there were more  simple... sequences immediately following, greedy  + would try to grab them, but there aren't, so it don't. If  + is satisfied with what it has, it can't force preceding satisfied assertions to fail.

In the  qr/(?:(simple).*?){3}/ regex, the  {3} quantifier cannot be satisfied until it forces the preceding  .*? to grab a bunch more stuff.

(I've removed the  /g modifier in these examples because it just confuses the issue.)

c:\@Work\Perl\monks>perl -wMstrict -lE
"my $re = qr/(?:(s \d mple).*?)+/x;
 my $string = 'This is a s1mple thing just a s2mple s3mple thing.';
 $string =~ $re;
 say $&;
 ;;
 my $string2 = 'This is a s1mples2mples3mple thing';
 $string2 =~ $re;
 say $&;
 ;;
 $re = qr/(?:(s \d mple).*?){3}/x;
 $string =~ $re;
 say $&;
"
s1mple
s1mples2mples3mple
s1mple thing just a s2mple s3mple
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