If tokens are whitespace-separated and there are always 5 of them in a set: 
use warnings;
use strict;

my $str = '1START   ACCOUNTA     XXXXXMA      12345     XYZ111        
+  1START   ACCOUNTB     XXXXXBR      12345     XYZ191          1START
+   ACCOUNTA     XXXXXNY      54321     XYZ131';
my $i = 0;
while ($str =~ /(\S+)/g) {
    print "$1 ";
    $i++;
    print "\n" if $i % 5 == 0;
}

__END__

1START ACCOUNTA XXXXXMA 12345 XYZ111 
1START ACCOUNTB XXXXXBR 12345 XYZ191 
1START ACCOUNTA XXXXXNY 54321 XYZ131

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In reply to Re: Parsing a long string by toolic
in thread Parsing a long string by Anonymous Monk

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