Timed Tests

Today while monitoring a study hall, I examined the two released components for the CAPT's reading test. I read the story, eight pages. The test booklet recommends thirty minutes to read the story before recommending forty minutes to answer the four essay prompts (a passing score would a solid page of written material).
I then thought about my students, many of whom began the year reading at the fourth to fifth grade level. Most of my students balk at more than two pages of reading in one session.
Then, I recalled the Lexile test that takes upwards of forty minutes for some of my readers. I don't limit the time because I want them to do their best. They respond to the "lengthy" Lexile test by taking a quick break when they begin to lose focus and then continue testing. The results have demonstrated decent progress from the start of the year.
But what will happen when these students who could achieve at a higher level on the CAPT given more than 70 minutes have to rush through the reading before writing four essay prompts?
If the State of Connecticut is interested in assessing learning (standards) then the amount of time it takes to demonstrate that learning shouldn't matter. Should it?