50/50 is a lie.
For the person working it, both sides often expect priority or "more" than 50%.
When someone wants to 50/50 me, I tell them, 51/49 is fine. But there must be a clear priority when there's a conflict.
Strangely, when I do this, the urge to 50/50 me usually goes away. I have nothing against working 2-4 projects. But there must be clear priorities, or I must be able to set them.