We see this problem in software, especially in DevOps and "agile" shops, because the process is so forgiving of delay. In a manufacturing plant, no product comes out until all the component parts are ready. So there's a "no excuses" culture about running out of parts, or having an assembly line station down unexpectedly. Software rarely has that.
Organizations with real "no excuses" cultures have spares and reserves. They have a backup plan if a key person is sick or unavailable, or something important doesn't show up. They have slogans like "two is one and one is none". This is seldom seen in software development.
[1] http://www.au.af.mil/au/afri/aspj/digital/pdf/articles/2014-...