I've noticed over the past few years that my shoe laces would untie themselves on a semi regular basis throughout the day. I thought that it was just down to the actual laces, it couldn't possibly be me.
Eventually I snapped and googled it. Apparently over time my knot tying skills and morphed into a tying 'granny knots', the knot was on a diagonal slant rather than straight across the shoe. A simple fix was to swap which bow to tie round the other.
1 day and counting and i've not needed to re-tie my shoes unnecessarily.
The new shoes are still giving me grief though.