Dig down twice after a panel

quarry.lua

@@ -168,11 +168,13 @@ local function rectPrism(depth, width, length, leftFirst)
     Logger:debug("Handling full inventory with target:", invEmptyTarget, " handled:", handleFullInv(invEmptyTarget))
   end
   Logger:trace("RectPrism:", depth, width, length)
-  for i=1,depth do
+  for _=1,depth do
     panel(width, length, leftFirst, checkRefuel, checkFullInv)
-    while not turtle.down() do
-      turtle.digDown()
-      checkRefuel()
+    for __=1,2 do
+      while not turtle.down() do
+        turtle.digDown()
+        checkRefuel()
+      end
     end
     leftFirst = (not not leftFirst) ~= (width % 2 == 0)
   end