No, but these things are to be taken into account.

  1. If you are soul copyright holder and content is not commercialized, yes you can do it.
  2. Many websites have a precondition (like Quora) that you need to attribute a link that the content was previously published in Quora etc.
  3. For joint copyright holders and commercialized content, permission from concerned (written) has to be obtained.
  4. If you sold your work as a ghost writer then you no longer have any rights for the content.
  5. In every writing assignment I did (ghost as well as original), it was always mentioned that I can use the content for my private purpose or private circulation. I was also allowed to reference my own (non ghost ) work in my future public and elsewhere. This was all in my US calculus text book contract and I guess this is the standard.
  6. This is the primary difference between being a writer and a Author. Author has more discretionary power with him. This is why organizations demand originals for ghost works, just to nullify Authors power.