With that said, sometimes it’s the fault of the shoelaces themselves. Loops that are too large (overly long shoelaces) can snag on items in the environment (twigs, branches, etc.) to become forcibly untied, and some very specific kinds of shoelaces can be too slick and/or too stiff to keep a knot firmly tied (Canadian DoD shoelaces for boots are both very stiff and quite slick when brand new, they need to be broken in to hold fast; some dress shoes have similar laces, albeit stupidly thin).