I am amazed when I travel to barns to do a saddle fit how many saddles do not properly fit the horse or the rider.  The best way to explain proper saddle fit to the customer is to use the comparison of starting to train in a pair of shoes that do not fit.  Would you be able to run comfortable in shoes that are too big or too small.  Now imagine that you want to ride and train your horse in a saddle that is either too big or too small.