Caveat: I am a current graduate student.
I have a very interdisciplinary committee. My home department is information science and my committee members are from electrical and computer engineering, communication and statistics.
My research stands at the intersection of social network analysis, privacy and surveillance studies and spatial statistics. I defended my dissertation proposal late last year and my literature review was ~50 pages with over 250 references drawn from 6 disparate areas.
Some of my other colleagues who work in Human-Computer Interaction (HCI) (itself a rather interdisciplinary field) have lit reviews around the 40 page mark.
I constantly feel that there is always more to read and really important classical literature on privacy (dating from the 1700s) that I should read but haven't read in depth.
Before, committing to a dissertation in this field, I used to work in theoretical statistics, specifically estimation theory. My readings were focused and significantly lesser in number than the juggernaut that my annotated bibliography has turned out to be.
Perhaps, more pertinent, TOREAD folder used to have 2-4 articles at any given time. Now, that is anything from 8-10 in addition to 1-2 books at any given time.
Therefore, in response to your specific question, Yes!, it feels like I have to read more now that I work in an interdisciplinary space to "cover" all the bases.