As you say, Lawrence, "Focus and Do Not Disturb setup has been made much more flexible, but this has come at the cost of much more complication."
I help several older or non-techie people manage their phones. If they want to be certain of peace at night, they simply turn their phones off and back on in the morning.
I could try telling these people: "Swipe down to see the control panel, look for the half moon in the Focus area, tap it, and you will see Do Not Disturb. This means your phone won't ring. Then in the morning, when you want your phone to ring again, swipe down to see the control panel, look for the half moon where it says Do Not Disturb, tap it, and you will see Focus. The word 'Focus' means your phone will ring."
I can assure most of these people would rather just turn their phones off and on. Plus, this will meet the NSA recommendation of turning mobile phones off at least once a week for security reasons without having to explain to them why they should do this.
Even for myself, I couldn't use a dnd schedule. I never go to bed or get up the same time two days in a row. I'd rather turn the phone off and on, too.