my %vols = (
    Ben   =>  5,
    Scott =>  4,
    Jim   =>  1,
);

my $batches = 98;
OUTER: {
    while (my ($v, $c) = each %vols) {
        foreach (1 .. $c) {
            say $v;
            last OUTER unless $batches--;
        }
    }
    redo;
}
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This may not be everyones definition of 'fair'. If you want Scott, Ben and Jim take one batch each if there are only 3 batches, the algorithm above won't work (but then, neither did yours).