My map has a winding creek that was originally made with one giant water brush. Knowing that water is rendered regardless of whether it's seen by the player or not, I figured I'd create the creek out of several brushes of fitting size so that there is minimal water rendered that isn't being seen. Is that better though? Would the source engine prefer to deal with one large water brush or several smaller ones? I feel like I did the right thing in terms of optimization, but knowing how some of these intricacies work I'm not so certain.

several smaller ones!!

I figured I'd create the creek out of several brushes of fitting size so that there is minimal water rendered that isn't being seen.

its exactly what should be done.

the more surface you have the harder it is to render.