Only advice - create new ones sparingly (unless you're MEP in which case they insist on a ton). Once you start using Worksets for visibility you fall back into an AutoCAD layer mindset. Use them for demand-loading the model if/when it gets too large to work with all the geometry loaded relative to your computer specs.

We've mostly gotten away from using Worksets as much as we can.
You're pretty much stuck wit Workset1 and Shared Levels and Grids, but beyond that, the only things we put on unique Worksets are (as Greg says) other things that are Linked in.
Beyond the two defaults, we have:

• Link-AutoCAD
• Link-Structural
• Link-Mechanical
• Link-Electrical
• Link-Equipment

As you can probably guess, the only thing that's on each of them in the one Linked Revit model
And it's definitely not for Visibility. Only to remove that Link from memory for performance purposes.

Two problems with Worksets:
1.) It's a manual process. YOU have to remember to put, say Furniture on the FFE workset. We found so many things ended up on the wrong workset because people forgot to change it, that it ended up being more work to fix them, and there really isn't a whole lot of benefit.
2.) When you make a new Local Copy (which you really should every time you Open a file), you're current Workset will be set to whatever it was when the last person SWC'd. So basically, you're getting what someone else saved. If you don't think to check that EVERY TIME, you'll be working along then suddenly realize that everything you've done for the last hour is on the wrong workset.

You can save the central with the option to force selection of Worksets at every open to get around this. And, without this, you can't unload those linked files in the rare event of an issue related to the linked files (if it opens with one/more of the links unloaded then something is most likely wrong with the links).

Even with Specify, though, isn't your Current Workset still set to the "last one out of the pool"?

Oh... current... missed that part of your comment. I'm sure you're right. I have no idea since I do my damnedest not to use worksets like that!

Only if they're doing it wrong...fewer the better from this MEP guy.

I base things off with the 1st level of the CSI Omniclass Table 21; Core, Shell (sometimes "CAS" [Core&Shell] for small projects), Interiors, FFE (combined in Int for small proj), Site, Services [Engineering] (combined into Interiors for small proj). For very large projects I may beak it down one more level with a full team of 12 users per model. Having this many users helps having extra worksets to unload & reduce the memory banks so "borrowing" can be made easier. Depending on the Project type may dictate modifications to this learned through your own best practices. For larger complicated projects (most of my time) I have consultants (sometimes sub-Arch group) all emulate the same Named Worksets to make it easier to collaborate/hide a group of systems with multiple categories that everyone may be utilizing at the same time. For one of those instances for example the Arch Levels & Grids get each their own Workset, but everyone else stays on "Shared Levels & Grids". Then for Worksets that are meant to be off by default have"..._Off" added to the names (noob mistakes of modifying workset settings unintentionally). Plus much much more strategies if everyone is not duplicating content, but utilizing from everyone's model...it's happened more times than not. Adaptation is the name of the Game that need to work with the processes/workflows being implemented for your team. It can be a moving target sometimes.