That is a good question!  Starch builds up on fibers like little coatings of primer.  Eventually with subsequent cleanings the starch will continue to build up putting weight and stress on the fibers of your items.  Shirts with excess starch get weak in areas were extra tension from normal use occurs. 

Eventually, stress tears will appear across the back or on the elbows of that crispy shirt.  They are big tears with some fibers broken and others still intact.  The weaker cross threads usually break first from the chemical starch build up! Sadly, it can’t be helped since the starch simply makes the treads brittle and weak. 

We recommend light to medium starch at the most!  Your shirts will last longer and still look wonderfully pressed and crisp with the buildup of heavy starch.