A well-crafted contract should protect the interests of all the parties involved. Problems to arise, however, which can go contrary to what seems like a very straight-forward agreement. A judge or jury may not share your idea of what is legal, reasonable or what makes a contract valid and in many cases specialized contracts need to be very specific to a variety of legal issues to work as intended.
Many people choose to use standardized templates or other resources in creating simple or often-repeated contracts. While many situations justify a quick template solution, it is also a valid idea for a quick and cost-effective overview to ensure what you believe is agreed to really will survive legal scrutiny and meet your needs.