Not needed. The only places with wrench flats on my bike are the brakes (where holding the brake with your hand works as well to keep the brake from moving on installation, and you only need to put a wrench on there when disassembling the brake for spring replacement every 15 years or so), pedals (where an 8mm hex socket works too, a standard open ended wrench doesn't always fit, and a pedal wrench provides more leverage), threaded headset (obsolete, and it takes a pair of 32mm wrenches which aren't in a basic kit), the cones and lock nuts (where only a cone wrench fits), and the nut holding some of my freehub bodies on (where a cone wrench fits and which you don't need to monkey with when building a bike).

An open ended is nice for cassette removal (you can see the tool is still seated well in the lock ring, and can even clamp it on there with a quick release if you want) although that's a 1" wrench not in metric sets and missing from small sets and using the same 1" socket you'd use with a torque wrench for installation works almost as well.