… is probably the opposite of, "this might work."
"This better work," is the thinking of safety, of proven, of beyond blame.
"This might work," on the other hand, is the thinking of art, innovation and insight.
If you spend all day working on stuff that better work, you back yourself into a corner, because you'll never have the space or resources to throw some 'might' stuff into the mix. On the other hand, if you spend all your time on stuff that might work, you'll never need to dream up something that better work, because your art will have paid off long ago.