zeusagis - you make an excellent point (well, several actually): the coasters have "not been run before continuously". No matter how many years a coaster is a prototype or how many computer designs it has gone through, little stress-testing can compare to a full day's operation in variable weather conditions (cool/wet in the morning, hot during the day, sudden storms, lightning), ride loads, winds, etc. Every new thing always takes some breaking in like that when you're considering how coasters are primarily specialized for the park/land/load/climate they are designed for. Even if you took a tried-and-true (let's say Magnum) and moved it to a different park, it would still have the breaking-in period.
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Po!nt of View: A different look at Roller Coasters.
http://www.crosswinds.net/~justmayntz/thrills/index.html