Of course they would be! And the water thing applies for casseroles and stews and other savouries, too, of course. Stock, wine, even tinned soup mixes can all be handy in those contexts.

(though I must confess I'm not 100% sure what biscuit mix is - I gather it is a bit like what I'd think of as a scone mix? Butter, flour, a little milk to bind, and don't overknead, yes?)

I'm glad you enjoyed the post, anyway!