Hochiki Europe has put together a great little guide book that shows where and how Emergency Lighting should be deployed in a facility. The guide book can be downloaded here:
Although the BS 5266 standards are slightly different than the US standards, this is still a good example guide to read for US venue operators as the basic principles are well documented and the graphic examples are clear and concise.
One of the leading failures of many emergency lighting systems is the battery. If the battery system is not maintained and tested they can fail to perform. The lights must be tested regularly, and they must be operated under emergency power for an extended time to ensure that when called upon they will light the way for safe egress from a facility.