No. B/c it's velcro there's a little elasticity, as there is with the
metal basket itself.
I attach the strips in such a way that there's opposing tension,
iteratively tightening them- if that makes sense. Pro'ly best to
start with the loop (nearest to the headtube), then each of the
corners, revisiting them to further tighten them, as you get around
the rack. That make sense? Akin to how you're supposed to tighten
the nuts/bolts on a car wheel.
Using zipties depends on the slight elasticity of the metal wires of
the basket- no different here.
Haven't carried a load o' groceries yet, but I think it'll be plenty
tight.
Tse-Sung