There are a few concepts that need to be clarified regarding asset protection.
You are facing two kinds of liabilities. Inside liability and outside liability.
Inside liability is when a claim arise from one of your asset, and it is threatening all your other asset (for instance a mold problem in one of your property and a tenant claiming major health issue resulting from it).
Outside liability when you are personally attacked for your personal actions or your kids through vicarious liability (think your son is involved in a DUI and kill someone whose family is suing you for damage). All the asset you own personally are at risk.
The goal of asset protection is to insulate all your assets in different boxes to contain the spread of an attack only to that box, and protecting all the other boxes.
For years, Limited Partnership was one of these boxes that was commonly used in the asset protection field. Today Limited Liability Companies are the most used entities as they are offering the same level of protection than LP in some states, but with much less formalities and cost. All states will offer inside liability protection for LLC, but only a few states are offering outside liability protection. WY is one of these states that have the charging order protection that limit the reach of outside liability claims. FL for instance also has charging order protection for multi-member LLC, but not for single-member LLC anymore (see Olmstead vs FTC). WY also does not publish the list of its LLC members, giving anonymity. Anonymity by itself is not asset protection, but is a preventative measure against contingency ambulance chaser attorney. If they can't see your assets, they don't know if it is worth to spend tens of thousands of dollars in a lawsuit where there is maybe nothing to collect.
On the other side of the spectrum, when you have a property in one state, you need your entity to also be legally existing in that state to be able to act in court. So you will need an LLC in the state where the property is located. Using a WY LLC that is foreign registered in another state is probably not a good solution as not only will you have to pay an LLC registration in both states, and more importantly, a judge may decide to apply the LLC laws of either state the most unfavorable for you.
So the most often used setup is to have a single member LLC in the state where the property is located. This LLC is then owned by a WY holding LLC. You get the best of both worlds. You keep the anonymity and the charging order protection of WY, while your local LLC can go to court.
If you have multiple properties in the same state, you can have all of them in the same LLC. But remember that if you have an inside liability claim arising from one of these properties, you are putting the totality of LLC's asset at risk. So it is probably better to have multiple LLCs to divide your properties in small chunk that you are comfortable to risk losing.
Now you raised another question regarding properties in CA. CA is a state where the franchise fee is $800 per LLC per year, while in most other state the yearly cost of an LLC is between $50 and $200. CA will also assess that franchise tax on LLC in other states doing business in CA. However this franchise tax is not assessed on trust. So for CA it is sometimes suggested to use a land trust (with some caveats) or a WY Statutory Trust to avoid this franchise tax.
Creating these complex structures has a cost, and if you are not familiar with some technicalities, it is probably not a DIY setup. Creating the LLCs is not difficult, what matters is their operating agreements that need to be drafted by an experienced asset protection attorney. This document is what will make or break your asset protection if you have to go to court.
Also operating these structures have recurring cost (annual LLC fees, registered agent). You also need to have proper bookkeeping, separate account, and proper operation procedures to avoid piercing its veil.
Taxwise, these structures are tax neutral and could even not require any other tax reporting if your WY holding is disregarded for tax purpose.
However, you can also improve the basic structure by adding some other features, like a management corporation in the middle, that can offer you some tax advantages and ancillary benefits.
Also, when creating such a structure, it is often recommended to have estate planning in mind as it is easily incorporated in it.
So ideally you would like to talk to an asset protection, tax, and estate planning attorney as all three fields should work together to make a comprehensive solution. One expert matter on only one field may have an excellent solution for that part, but be disastrous for the other.
I would highly recommend that you check the Youtube Channel of Clint Coons. I have found his very detailed videos excellent and I am in agreement with most of his advice. By educating yourself you will not become an expert, but you will know enough to assess what you need and if what is offered to you meet your goals.
At the end of the day, the level of asset protection you need is a personal choice. Some people are happy with $250k umbrella insurance. Some wants $10M. Some wants one single LLC. Some wants one LLC per property. It is whatever makes you sleep at night.
Personally I am using insurance and I have one LLC per property and a WY holding LLC. In the big picture, the cost of these LLC is negligible compared to all the other insurances I am already paying. I see it as another cost of doing business. But I am also confident that if I am unlucky and find myself on the receiving end of one of these rare, but catastrophic lawsuits, my family asset will be protected.