I have previously used DayOne to record my professional daily routine to assist with time record for billing purposes. This approach was short lived as I soon returned to using the visual interface of Fantastical2 and its ability to use native language text entry.
Now using DayOne2 for journaling the build and modifications I am doing to my Toyota FJ Cruiser to prepare it for off roading and future overlanding trips.
Works well to document photos from the iOS Photos app. Can even recognize previous dates and locations when exporting from Photos to DayOne2. This has enabled me to add post dated entries to complete the story so far.