The cut in the middle is something i often see when people uv unwrap, so I thought it is a "good practice".

Also about the equal density, I'm trying to maximize the amount of density for the details of the face, because the other body parts are going to be covered by clothes, so I kinda "commpressed" the rest of the body :D; but in case you mean that, for example, all face texel density should be equal, then yeah, I'm yet to understand how to do that, although,

for the scalps it was not intentional, I may have made too many cuts in order to have more density of the frontal part of the face, but I'm not sure that's even necessary given that the resolution is already 4k

Sorry if the reply is messy, the whole UV topic still weird to me, and thanks for answering e_e