I have a few Phals that do that as well, and noticed that it seems related to the amount of light they get. In brighter light the leaves are narrower since it needs less surface area to capture the same amount of energy as a wider leaf. I non-scientifically tested this by putting a plant (a schilleriana cross) in a bright spot for 1 leaf growth and a shady spot for the next leaf. The first leaf was narrow and the second was wide. N=1, so I can't exclude other cultural factors which may have varied.

“Old timers” told me “round leaves, round flowers”, so when selecting seedlings I chose rounder ones. Is that true? Got me.

these are weird Phal leaves from light orientation, being in a bag, being moved, and other unknown factors.

https://live.staticflickr.com/65535/...01b2f67_4k.jpgPhal leaves by J Solo, on Flickr

https://live.staticflickr.com/65535/...c47353e_4k.jpgPhal leaves by J Solo, on Flickr

https://live.staticflickr.com/65535/...6234eeb_4k.jpgPhal leaves by J Solo, on Flickr

https://live.staticflickr.com/65535/...c76a34f_4k.jpgPhal leaves by J Solo, on Flickr

https://live.staticflickr.com/65535/...f5ab48c_4k.jpgPhal leaves by J Solo, on Flickr

https://live.staticflickr.com/65535/...2d604c3_4k.jpgPhal leaves by J Solo, on Flickr