I'm creating pull request that I approve and merge myself. In the end they are registered and can be consulted in the remote repository, but I do not know if it makes much sense to do this or there is a better mechanism, such as the use of tags.
I use them by habit and for ease, in personal projects and I do not know if they really are useful or it is work that is over.
Working in BitBucket ... each platform implements pull-request in its own way.
Can be created without assigning a person for review, which you can do yourself.
Pull-requests have a title (and description), so they allow you to group sets of commits, being able to take a quick look.
Saved messages are a way to store "summarized" the work history, as a 'changelog'. For example, You can have 800 commits and 20 pull-request .