Do shield size have different parry windows?

I’m curious about how the different shield categories (small, medium, large) affect the parry window. Do small shields like the Buckler have a wider or more forgiving parry window compared to medium shields? Additionally, is the Buckler considered the best shield for parrying in Demon’s Souls, as it often is in other Soulsborne games? Or are there other shields that are equally (or more) effective for this purpose?