Bridge Calibration tower

As commented the original has the holes in the sides interrupting the ability to form a good bridge on the cross section, which makes calibration difficult.
I set these up in 3 towers testing .8, .9, 1.0 extrusion and up the towers I change the speeds using S3D Variable settings wizard
Result: Get the answer in one go { unless Im unsure about themperature :-( }
And having multiple towers stops unwanted variable of sag due to lack of time to solidify ( like when using ABS without fan )