At my last "real" full-time job, developers could accumulate vacation time that was not used in a given year. Sometimes it was on purpose, so as to take longer vacations later on, often it was required because of deadlines, staffing shortages, whatever.

Then one day the new company owner declares that vacation time could no longer be accrued. Use it or lose it. Some folks had many weeks of time saved up.

The owner said that people can use up what they've already saved, but added, Keep in mind that if your department can afford to do without you for several weeks then perhaps you're not so essential. He all but winked when he said it.

This was just one of the things that convinced me to just leave and work for myself.