DD is in primary care. She also has two young kids with usual assortment of school and preschool-related illnesses. So, she sees the issue from both sides.
Her practice had so many no-shows that they instituted a policy of two no-shows in a row means you don't get another appointment. Go somewhere else. Also, chronic late arrival gets a "last appointment of the day" designation.
For her own kids, she is fortunate that DH can usually work from home but sometimes she has to cancel. Kids come first. They try to reschedule within a week or so which means doubling up/no lunch and it's very stressful.
When I go in for my annual, I have list of every test/visit I've had for the year - mammo, pap, dentist, derm, whatever. Also every medicine or vitamin. My primary says I'm one of the few patients who does this and it saves so much time. He says with some people "it's like pulling teeth" to get a history. My DD echoes this.