As Paul says every block with data in it must be read - even for an incremental backup. Which is why an incremental backup takes about as long to run as a full backup.

-Bp 10 helps to prevent the entire -B buffer pool getting flushed as a result of a backup running and the follow-on impact that that will have to the hit ratio. During the backup itself though you will still almost certainly see a poor hit ratio.

I dunno, you're a pretty shady character...

Oooh shiny!

Except for a few weirdos base = 1 is kind of the norm 😉

(I do understand your use case -- I do that too although probably less often than you seem to. But it is helpful to verify that ProTop is behaving as expected.)