If you're running out of cron here, and not daemonized, and if you get a chef run that sticks and never releases the lock then chef-clients will pile-up on this lock.  I don't think this applies to daemonized mode, but we support running chef out of cron.   The typical pattern here is either to use the pid file to assassinate the stuck daemon (the rude option) or to timeout after awhile and give up on trying to acquire the lock (the nice option).  For my own servers I've always used the rude option and it is clearly better when you can do it, since it solves the problem for you.  Knowing that we have users who have obscenely long chef-client runs, we probably can't do that, and need to use the nice option.