I would not be able to say the quantities/yields from recent productions, although 30 years ago we were making approximately 45 pipes per day. Of these 45 finished pipes, we would have 'scrapped' 8 or so (and at the earliest stage possible) as we did not want to take one 'all the way through' production only to scrap it at the end. Say 20 or so would have been Tilsheads roughly 50% Natural and 50% dark, say 6 'S' grades 14 'P' grades, 3 'B' grades, 1 or 2 'G' grades. On another day, we may have 1 or 2 Bs, 1 G and an E or an X. Something like that anyway. There would be times when we were 'on a run'. The area where they were digging briar was far away from any footpaths, so the briar was not subjected to its branches being broken off for the inhabitants' firewood as they passed by. This 'branch-breaking' causes stress to the Xylem tissues/'veins' (as Pete explained earlier) and causes distortions, stress cracks in the burl etc. 'On a run' it has been known to yield 2 or 3 XX, 2 X, 4 Es, 5Gs, 5 Bs, 6 Ps and 2 S grades a day.