Mapping is re-using the buffer but you can choose either/both options. swapping does reduce the need for fences/synchronization, however you will have to keep track of the buffer to make sure you don't leak it

Btw, on the xbox one, you can use the community dev mode to make indie games. A full devkit will costs several thousand dollars and I believe msft restricts who they sell to

the question was changed after I wrote this answer