I tried a few ways, but they all seem to burp a couple of seconds once in a while even when niced. Shouldn't miss a whole minute though if you set $duration to 60. 
#!/usr/bin/perl -w
use strict;
use Time::HiRes qw (usleep);
$|=1;
my $duration = 2; # seconds between job starts
my $maxsecs = 30;
my $tinit = my $t0 = time; my $t1;
while (1) {
  $t1 = time;
  last if $t1-$tinit > $maxsecs;
  if ($t1-$t0 >= $duration) { # if delta-t >= d secs
    &act;
    if ($t1-$t0 > $duration+1) { print "(",$t1-$t0-$duration,")" };
    $t0 = $t1;
  }
  &waitfortick;
}

sub act {
  print "tick\n"; `boop`; # same 100% volume
}
sub waitfortick {
  print ".";
  #&sleepwait; # try these three separately
  #&selwait;
  &hireswait;
  `beep`; # from xtune, does wave -d 0.01 -f 250 -l 30
}
sub sleepwait { # tick approx 1 sec
  sleep 1;
}
sub selwait {
  select(undef, undef, undef, 0.10); # wait approx 100 millisecs
}
sub hireswait {
  usleep 100000; # sleep 100,000 microsecs if you have usleep
}

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In reply to Re: Reasonably accurate timing by mattr
in thread Reasonably accurate timing by traveler

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