Though insurance companies have an incentive to pay the least amount of money possible in short term and long term disability benefits, most the time you will not have a problem if your injuries are obvious.
Even where the injuries are obvious, however, you may have problems if you do not receive benefits within a month. Call a lawyer if this happens.
If you are receiving long term disability benefits and the insurance company informs you that they're reviewing your right to receive benefits, you should contact a lawyer immediately. This review process often occurs when you are approaching the period of time in which the definition of disability changes. As noted in answer to an earlier question, after two years, many long term disability policies provide that you have to be disabled from all employment to be entitled to continued benefits. It is at that time that many insurance companies investigate your right to continued benefits.