This is a good question and the level of reinforcement really depends on where the ski is mainly intended to be ridden. Skis intended for mainly flat water use or very small surf where weight is an issue, need less reinforcement than a ski intended to be ridden in large surf. A ski intended for large surf riding which will be jumped at much greater heights will obviously need much more reinforcing. Fortunately weight is not such an issue on a large surf ski as a heavier ski actually handles better in sizeable surf. Before reinforcing, a better question to ask would be what type of riding the ski will be mainly intended for, and then reinforce accordingly.