Aerification of greens, tees, fairways, and rough have many benefits. Decreased compaction, improved air and gas exchange, thatch removal, and amending the profile are just naming a few. Every golf course is different in terms of climate, grass varieties, soil composition, nutrient levels, and amounts of traffic. This means that no two courses can be managed the same, and for that matter no two greens can be managed exactly the same.
Throughout the growing season we implement many cultural practices to improve turf health and conditioning and more often than not they are directly related. Many golfers know the term aerification and have heard terms such as "needle tinning" or "venting" but may not exactly know how crucial these practices are to keeping healthy, playable turf.
Recently we aerified a green on the north course that was starting to show signs of stress related to compaction of soils and a lack of oxygen. After months of mowing, rolling, and having plenty of golfing traffic on the greens, it's not uncommon to see issues by August. Most superintendents, including myself, use "needle tinning" to poke very small holes in the putting surface therefore allowing air and gas exchange as well as reducing some compaction with very minimal impact to putting. In rare cases it's necessary to use a larger hole to improve conditions and ensure healthy turf through the end of the growing season.
To better explain why it's necessary in some areas and not others, I have included a few photos to show the difference in greens below the surface. Sandy soils will not compact like heavy soils will under the same traffic stresses and therefore will act much differently at the turf level. In addition, a green that is built correctly will allow for the entire profile to hold or release moisture evenly and consistently.