More choice can make things harder, rather than easier. Being faced with row upon row of A-Z authors can make the most confident reader dither. Do you start at A or Z or somewhere in the middle? This is why many readers latch on to a favourite author or series and only come unstuck when they get to the end.  Every library assistant wishes these favourite authors would produce ten books a year and live forever.  Categorisation is a help but then you get readers who won't risk moving outside their familiar category.

Surveys of how readers choose fiction in libraries have shown that most regard libraries as a lottery. It is pure chance what happens to be in at the time and what your eye happens to light on. A few people are searching for a particular book or author; more recognise a familiar author or title while browsing; the majority check out the returns trolley, where a completely random selection of 'hot' books, jumbled without any arrangement or classification is small enough to offer manageable choices.  Up to 50% of all issues have been shown to go from the returns trolley.  A tiny proportion of stock is working to tremendous capacity while acres of books lie untouched on the shelves. 

What are the lessons to be learnt from this about promotion?