I don't. I'm one of those rare persons who still has a land line, so I can always be reached. Each night, I put my iPhone in airplane mode. No disturbances from my iPhone (plus it keeps its full charge until morning). Anyway, you're right, people can simply play with the settings to achieve different results.
You don't need to put your iPhone in airplane mode at night. Just set the Do Not Disturb, and be done with it. Allow your messages to come through with no disturbances. . . You can still call out if you want. Set a time for when it is inappropriate for people to disturb you and set that as when you won't be bothered.
I don't go to bed until the wee hours of the morning, but my iPhone Do Not Disturb is set for 9PM. The only people who can get me after that are close family and friends whom I've put in my VIP list or someone who dials my number twice in succession with a short period and they better have their tail end on fire.