Timber decking done right

I am often told by prospective clients that other decking contractors have told them that they do not need plans or an engineered design for their timber deck, because, among other reasons, their deck will be located at a private home, will only be utilised by one or two people, or will not be high off the ground. This is simply not true and the general rule is that if anyone can get injured due to a structural failure, like a decking slat breaking, for example, then an engineer (a civil or structural engineer, who is qualified and competent to engineer timber structures) should be engaged to check the contractor's design.