OSM is constantly changing and no matter how filled out an area on the map is it is never done. The impression that validating a grid will mean that it will never be revisited leads many to feel intimidated by it. Anyone can validate! Just remember, do not validate your own work.
Validating a grid means that everything that needs to be done to meet the goals of the task you are working on. If the task is to map every type of feature possible and provide attributes this may be very complex and may require field verification but if the goal is to map basic features in a sparsly populated area this process is fairly straight forward.