That'd work, the only catch being that when you see 1 you need to know where 2 is, and it's on the other side of the mattress (I have a latex mattress, it weighs about 30kg so it's a pain to turn over, even to look. Turning it twice because you got it wrong with the first movement is a big cost.)

You don't actually need to remember which instruction to read, cos they're the same on the each side of the mattress. I could have just written "side to side" on one side and "top to bottom" on the other side, it'd just sometimes be upside down.