What are reasonable accommodations? Reasonable accommodations, according to the Rehabilitation Act of 1973, are modifications which may, “…include changes in the length of time permitted for the completion of degree requirements, substitution of specific courses required for the completion of degree requirements, and adaptation of the manner in which specific courses are conducted.”
Accommodations vary from college to college as in one study most professionals agreed that accommodations should be provided in the class room, but to what degree varied. However, in another study up to 25% of the professors polled stated that, “…faculty should not accept alternative assignments or provide copies of lecture notes to students with ADHD.”  Why accommodations vary or even be denied is a question for which I could not find an answer, but ADHD students do benefit from accommodations. Noël Gregg and Donald D Deshler suggest a possible answer to this question: “The most significant barrier facing individuals qualified to receive specific accommodations is the lack of professional knowledge about issues pertaining to these accommodations.”
However, I think professionals within the realm of upper academia want individuals with ADHD to succeed in school as those with ADHD typically rate just as intelligent or above compared to their peers (Non-ADHD).  Unfortunately, it seems few with learning disabilities (like ADHD) use academic disability services. There seems to be some truth to what Gregg and Deshler suggest. If there is an underdeveloped understanding of what accommodations are by those who will be the gatekeepers (Deans, Professors, etc) to those accommodations then this poses a major problem. My prayer is that college institutions seek to understand accommodation law and what needs to be done to follow it.
 Vance and Weynandt cite a study done by Nelson, Dodd, and Smith writing, “Nelson, Dodd, and Smith11 sought to evaluate the instructional practices of faculty when students with learning disabilities were present in the classroom, as well as to identify if differences in willingness to accommodate students were apparent among the academic departments. A questionnaire sent to 141 faculty in a northwestern college indicated that
faculty were willing to provide accommodations to students with learning disabilities. Responses varied, however, on what type of accommodations should be provided.” Vance, Teresa Ann, and Lisa Weyandt. 2008. "Professor Perceptions of College Students With Attention Deficit Hyperactivity Disorder." Journal Of American College Health 57, no. 3: 303-308
 David Kraft reports that, “Although ADHD students often showed strengths in attitudes, information processing, and the use of study aids, they had weaknesses in test strategies, selecting main ideas, and concentration, compared to their peers. Many students with ADHD benefited from accommodations for standardized testing and classroom testing (such as extended time to overcome distractibility and slow processing speed), small group or individual teaching methods (to overcome distractibility), and/or computerized documents (to counteract cognitive-organizational problems). Teachers may also want to use oral exams, take-home projects, or more frequent exams covering smaller amounts of material with ADHD students.“ Kraft, David P. "Nonmedication Treatments for Adult ADHD: Evaluating Impact on Daily Functioning and Well-being, by J. Russell Ramsay, PhD." Journal of American College Health 59, no. 1 (2010): 57-9; There can also be a inference argued that ADHD students do not usually finish secondary education reasonable accommodations would greatly help. Reaser, Abigail, Prevatt, Petscher, and Proctor write, “Students of all ages with ADHD are at risk for academic achievement problems and school failure and are less likely to complete a postsecondary education (Barkley, 1998; Faraone, Biederman, &Lehman, 1993; Gaub & Carlson, 1997).” Reaser, Abigail, Frances Prevatt, Yaacov Petscher, and Briley Proctor. 2007. "The learning and study strategies of college students with ADHD." Psychology In The Schools 44, no. 6: 627-638
 Gregg, Noël; Deshler PhD, Donald D. (2009-01-16). Adolescents and Adults with Learning Disabilities and ADHD (Kindle Locations 348-351). Guilford Press. Kindle Edition.
 Prevatt, Frances, Abigail Reaser, Briley Proctor, and Yaacov Petscher. "The Learning/Study Strategies of College Students with ADHD." The ADHD Report 15, no. 6 (2007): 6-9
 Meaux, J. B., Green, A. A., & Broussard, L. L. (2009). ADHD in the college student: a block in the road. Journal Of Psychiatric & Mental Health Nursing, 16(3), 248-256