According to the article cited by Neil, "New medical articles are appearing at a rate of at least one every 26 seconds, and if a physician were to read every medical journal published they would need to read 5000 articles per day" (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3191655/).
It should be noted that the first part of this quote (from a paper published in 2010) is based on papers published almost 40 years ago, and the second part on papers published more than 20 years ago. The original data cited in those papers must be older still. Does anyone have any newer data?
Having said that, the information overload and redundancy is certainly getting more and more severe as the information age progresses. In fact,there is so much redundancy in the information age that, according to one article, there are over 75 names for it – information revolution, age of access, communications age... [it's another ancient article - Doctor, R. 1992. Social Equity and Information Technologies: Moving toward Information Democracy, Annual Review of Information and Science Technology (ARIST), Volume 27, Chapter 2.]
Time for someone to come up with contemporary data on this age-old problem.
HIFA profile: Chris Zielinski: As a Visiting Fellow and Lecturer at the Centre for Global Health, University of Winchester, Chris leads the Partnerships in Health Information (Phi) programme. Formerly an NGO, Phi supports knowledge development and brokers healthcare information exchanges of all kinds. Chris has held senior positions in publishing and knowledge management with WHO in Brazzaville, Geneva, Cairo and New Delhi, with FAO in Rome, ILO in Geneva, and UNIDO in Vienna. Chris also spent three years in London as Chief Executive of the Authors Licensing and Collecting Society. He served on WHO’s Ethical Review Committee, and was an originator of the African Health Observatory. Chris is the elected Vice President (and President-in-Waiting) of the World Association of Medical Editors. He has been a director of the UK Copyright Licensing Agency, Educational Recording Agency, and International Association of Audiovisual Writers and Directors. He has served on the boards of several NGOs and ethics groupings (information and computer ethics and bioethics). chris AT chriszielinski.com. His publications are at https://www.researchgate.net/profile/Chris-Zielinski and https://winchester.academia.edu/ChrisZielinski/ and his blogs are http://ziggytheblue.wordrpress.com and https://www.tumblr.com/blog/ziggytheblue