Test piece for speed, jerk, acceleration as well as ringing, vibration, vertical banding and other artefacts.
Ran some tests on my CoreXY printer with two " Test part to look at X and Y damping and resonance by MiseryBot", but realized, that it was too small.
This part has the 45° and 135° you also want to test on a CoreXY machine integrated. And the parameters you vary can be embossed.
The example STL was printed with acceleration 2000 / jerk 20 on X and acceleration 1500 / jerk 12 on Y.
Speed was set to 100 mm/s and edited in Gcode to be 50%, 100%, 125%, 150%, 175% and 200% - two speeds per line of text.
In this run I forgot to also raise the temperature. ;-)