Conical slices were compared with tilted slices, which are also used for belt 3D printers. Both have some geometric limitations. Tilted slices can only print the overhang in one direction ...
If you want better 3D-printed overhangs, you need better cooling ... full of water when they came off the bed. The next obvious test is to do the printing in a public swimming pool.
For calibrating your 3D printer, Benchy isn't the only game in town. Here are other 3D test models you can use to dial in ...