I have a Cali journeyman but unless something changed there is no Cali Masters.
Taken a lot of certification tests in my time, Cali was probably the easiest.
So the next question is what state/municipality?
From that you can figure out who the test is from and who administers the test.
Such as ICC (International Code Council).
Had a Clark County NV master and Kentucky master.
The tests seemed about the same except for a few local amendment questions at the end.
Same amount of time, questions, rules, testing centers, and even blueprint.
Where other areas write their own test and the questions may not be as straight forward. Few places require a hands on test, bring your tools and bender.
Before you worry about studying you need to qualify.
That can be a process right there.
The trouble is different states have different requirements that are not compatible with travelers.
Such as Texas. You need a master electrician to sign off you have 12,000 hours experience. But wait, Cali doesn't have a master electrician level.
Or Colorado. You need a notarized company letter of all your hours from your work places. Here it's common to get that when you leave a job. But not other places.
It's not easy for a bridge burner like me.
Not saying there aren't other ways to be qualified in those states, just that it's not simple.