Works well until you encounter a new keypad layout (eg when going abroad). I locked my card once like this although I had been typing the code for years before.
Android has this "draw a path through some dots in a grid" analogue to a PIN code. On the boot screen, the grid is a somewhat different size than on the unlock screen. This defeated my muscle memory, and my conscious memory had lost its backup.
My mum frequently punches in her postal code instead.