3 years fixed term jobs

What's your thought process if you decide to accept a job that's 3 years fixed-term?
What happens after 3 years? Do you plan to stay for 2 years and start job hunting in the 3rd year so by the time the job ends you have something lined up?
Have you done this before?
Just curious.
Comments
I have done a few contracts, and I have completed all of them successfully. In my case the staffing agencies were never 100% aware as to when my contract ended. I worked one contract were the staffing agency asked "do you know when your contract ends, did you get an extension?" This happened because, the staffing agency didn't know if there was an extension or not. Also, they couldn't reach the site contact. To be honest, I have had a few recruiters tell me that the company ( client) that is using the staffing agency is less likely to provide feedback(when does the contract end, is this contractor a good employee ect), unless there is a problem with the contractor.
I had to find jobs on my own, when my contracts ended. The last time I had a contract, I etched the end date in my mind,and I started looking for work before the contract ended.
--Alexander Graham Bell,
American inventor
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