Unless you are in a specialist or technical role where you have a story book type of CV, a CV of 2 or 3 pages is more than enough to engage the interest of a potential employer. The first 10 years of your employment history is the most relevant and anything beyond this would be recommended to be added to the CV in lineage.
Remember it is the quality of the CV which is important and not how many pages! It is more fruitful to have 1 page of interesting and relevant information rather than an extra few pages which have no purpose at all.