I season some of mine.

It makes a difference. Now I have sheets just for baking things that I want to brown more, and sheets for things I don't want more browning.

Just like cast, the seasoned baking sheets are nearly non-stick (especially if seasoned using Flax seed oil). Great for air frying potatoes in the convection oven, or bacon, etc.

Things like cookies get the un-seasoned sheets.