You be the judge: should my boyfriend double-knot his shoelaces?

I double-knot the shoelaces on my boots for example, because the laces need the extra help, but my Converse shoes work fine with single knots. Derren, meanwhile, laces up his shoes very loosely – I think he’s got weak fingers – so he really should tie a double knot every time. I have told him this, but he says he doesn’t like undoing them at the end of the day.