My children self weaned between 3.5 and 6 years old. During one year, I was nursing three children.
I found that nursing the older one for one minute per side, reduces the milk pressure for the younger two, especially after your milk comes back in after a new baby.
Placing your nursing baby on one side with a sibling on the other (rugby hold and a good pillow) builds strong sibling bonds. The child often held the hands and stroked the face of the younger baby whilst they nursed.
They are much older now with the oldest two at university and college. They know they were breastfeed as nursery/reception aged children and this has not stopped them doing well.
Nursing a 6 year old child (at bedtime, a couple times a week), is just as natural as a nursing a new born baby (on demand day and night). It is so frustrating that the world holds up one of these actions, as supportive and the other as destructive, when they are both stages of the same loving mother child dryad.
I guess people don't understand unless they have nursed an older child themselves. After all no one sets out to nurse an 6 year old, you start with a baby and nursing an older child just happens, day on day as the child grows older.
We all want secure, well loved children and extended breastfeeding is one way to achieve this goal.