According to Trendwatch, catalog publishing projects typically undergo 4 proofing cycles before they are signed off. Book publishers add even more proofing cycles to their catalog projects.
Why should you care?
With all the focus on printers, RIPs, and color profiling, it's easy to forget that most people proof jobs to catch basic mistakes. Take catalogs (please!). Since their primary purpose is to sell products, it's important that things like descriptions, phone numbers, SKUs, and prices be meticulously checked. Likewise, book publishers' catalogs are their most important selling tools. One incorrect ISBN can cause innumerable problems. If this is the primary purpose of proofing, does that mean that color is secondary--or is "good enough" color...well...good enough? And if so, is it any wonder that low-tech proofing is so popular?