I'm the same as chscag, got the basics down but not yet readt to enter into the more complicated areas.
I get that you can set times for certain activities and apps that are allowed to intrude on these activities eg you can create custom sets other than the defaults, Work, Sleep, Personal and Do Not Disturb so I created one called Nap. I gave it a time sensitive trigger 4pm-5pm and selected certain apps that are allowed to disturb me during that time. I could just as easily have had none but I chose, Starred contacts (favourites) and repeated phone calls. I could have added iMessage or WhatsApp if I was expecting an important message.
My Sleep setting is also time activated at 10pm-8am and the same exceptions ie. Starred contacts and repeated phone calls.
I leave DND to use as a anytime option like before with the same above exceptions.
The rest of the settings like Location triggers for say, Exercise (when I get to the Gym) or Work ,when I get to my workplace don't apply to me.
I think the most important part is setting the "exceptions," apps that can disturb you during these set or selected periods. I pretty much have none for all.
Then there is Focus Status. I believe this is On by default. If you pick any of the Focus states like Sleep you go to the settings page for that state and under options you will see Focus Status, click on that and you get a page which explains the preference. To me it simply means that people or apps that try to notify/contact me receive a message to say that I presently have notifications silenced and they get the option to send anyway.
After the time expires you get a list of notifications that you missed during that focus period.
I have left this on.
So, you can see that really I'm using Focus pretty much as I would have used Do Not Disturb it just allows more automation, additional time schedules and different triggers plus the option to choose multiple exceptions.
If I was 21 again, had a 9 to 5 job, weekends off, regular gym program, yoga classes on Saturday morning and a community church meeting every Tuesday night I could see the value of a lot of all these options. For me, DND with the addition of Sleep (which we already had) is all I need.