While Tresiba is known as a basal insulin with a flat action profile, it is not “flat” for the entire 42 hours of average duration. Taking Tresiba every 24 hours overlaps the reduced tail of the previous day’s dose. This additive effect yields a dependable steady state of insulin when taken every 24 hours.
As I’ve said before, I have personally witnessed the timing flexibility of Tresiba. When I forgot to take my Tresiba bedtime dose, I just took it the next morning and resumed my bedtime dose that same day.