Buffer size & Rescan on full buffer information

[Confucius Of Essex]

Hello,

Can you tell me more about the "Buffer size" & "Rescan on full buffer" on the "Network Drive"s tab, please?
How much work, changed info etc. is needed to fill it?
Deleting how many files would trigger a rescan?
What size should the buffer be?
Basically, I'd like to now how it works!
Thanks very much.