The amount of material that is actually read by a person has a positive or negative affect on reading ability. Many students do not read unless it is for an assignment in school. Any type of reading, such as fiction, nonfiction, news, magazine articles, recipes, instructions, reviews, and so on, would help a person become a better reader. Certainly, reading something the person finds interesting would be best. But, reading something because it is helpful is good too.
The reason for the positive affect is that increasing exposure to reading a wide range and amount of material increases a person's resource of neuron connections in the brain. The greater number of connections made while reading make it easier to understand and retain new material. This is why older adults often make excellent college students. They have so many neuron connections to relate to new information. It takes much less effort to understand and remember new material. Of course, stress can interfere with retaining information. And, many adults who are attending college are also under a great deal of stress. So, it might even out.
It actually seems to distress some students when they are required to read directions or material for an assignment. This could lead to a lower level of comprehension too. I find having students read directions and material aloud to me helps their comprehension.
Hopefully, the newer tech devices will renew an interest in reading.