This may not be an issue. For example, say the general power of attorney is triggered and the agent is a trusted friend. That agent could still be the right person to make decisions on your behalf.
Or it may be a huge issue. Take that same trusted friend at the time you signed the general power of attorney and over time the two of you have grown apart. He is living his life in Maine and just cannot put the right amount of effort into your situation as either you or he wants.
Another issue may be the grants in the will. For example, if the will gives all assets to charity, that may have been the right decision when executed. What happens now that there is a spouse and kids? Should the will be executed according to its clear intent? Or is the intent modified based upon the subsequent major events in your life?
These are difficult questions and an attorney who does estate administration should be able to answer them at the time such issues arise. However, it may lead to a longer and more litigious probate process. Taking the time and money to review the estate plan every several years, or when a significant event occurs, will reduce the risk of contested probate.
An updated will and estate plan will allow you to update your desires to reflect your situation. You will be able to give to your children, your spouse. You can update the specific gifts to reflect those items you just recieved or bought, such as that new house or heirloom from your parents.
Every little review of the estate plan creates peace of mind. That is a goal worth achieving.