just the opposite, I tried to apply a sphirical map to a cubebox, and "It eliminated polar pinch".
https://discourse.threejs.org/t/why-singularity-still-exists-after-i-split-equirectangular-map-to-cubic-map/5929
I hope this helps.
this is full code and results: https://jsfiddle.net/xiaoming110/bsouhvrt/37/