You hardly ever see frogs these days anyway, they come on pressed
bricks.
Most bricks are extruded and wire cut nowadays.

and some have to be laid cut direction down so the face doesn't hold
water... ....

Cheapskate brickies lay them frog down because it saves a lot on
mortar. They frog stays more or less empty.

causes all manner of swearing if you try and attach something like
a new door frame with frame anchors and you drill into a stonking
great void.
#
wasn't talking about bricks with frogs...