No I don't think the film gets over exposed in 3 second. Although I've often heard stories of folks staring at a page for many minutes while their brain went off into a daydream. They usually complain of not remembering one word of what they read.
1 second per section is enough... trust your brain. 3 second can be how fast you superread and dip... so I suggest you turn the text upside down if you intend to spend that long per section. 3 seconds is enough to take you out of photofocus and bring the conscious mind into attempting to read the text.
Alex
