The idea is that shorter awards will be made of say 2yrs if people are likely to improve with most awards being no longer than 10yrs. Only a small number of people will recieve indefinite awards. As PIP is so new we do not have any statistics, that I am aware of, around length of awards. However members may give their award lengths.
Care or supervision is as reasonably required rather than necessarily as provided. Other things should be taken into consideration as well such as whether someone is safe to do a task, whether it takes a long time, whether they can do it repeatedly, whether they can do it sometimes but not others. They are also supposed to consider side effects such as pain, fatigue, breathlessness.
If an award is gained before 65 it will continue untill it is due to be renewed. If it was then lost an AA claim would need to be made.