I attended a Wilderness First Aid course last weekend. The instructor reported several real-world scenarios. One was a group day-hiking a popular 8-ish mile trail in the Shenandoahs. Lady fell and busted up her leg about 4 miles up the trail on the way out, about 2:30 in the afternoon.
No cell service.
Someone walked out to find help, lucked up and met a ranger within 30 minutes.
It was 12:30 the next morning before they got her to the trailhead.
You can't be prepared for everything, but you can be prepared enough to avoid becoming another patient, even on a short day hike.