More worksets don't help unless people USE them wisely. That means not only assigning elements to them correctly but also being selective about opening and closing worksets that are not necessary to what I am doing right now or for the next little while. If you have a good workset scheme then I can close a chunk of the building while I focus on something for awhile. For example you don't need worksets for upper floors in the hospital open while working on labs on a lower floor. If you can't do that then your scheme isn't supporting workflow well yet.
The point of books on shelves is to be able to ignore irrelevant shelves to focus on the ones I care about now. You can also ask Revit for permission less often if you select many things (that you intend to work on right now) and use Make Elements Editable to borrow them all at once. You'll experience less pausing if you do. Each time you alter something you haven't already borrowed you are waiting for Revit to check to see if it can let you do it.
The more concurrent users there are the more important careful workset use and manipulation becomes.
Splitting models seems the easy fix because we understand that process from other software. Every time we split a model we pay a price in poorer integration of our data. They also introduce a further fragmented workflow and graphic quality issues.