For me it is about timing. I split my Levemir into two injections a day, and take an equal amount for the two injections. I take my morning shot when I wake up (about 8am). I tried taking my evening shot 12 hours offset at around 8pm, but that was too early, and I would wake up with dawn phenomenon (high blood sugar) pretty much every day. So instead I tried taking it later and later and finally settled on taking it at 11:30 PM (I set my cell alarm to go off every night - it warns me to take my insulin and turn on Steven Colbert). I imagine some of my dinner insulin is covering the morning Levemir that is wearing off, but that is easy since I’m taking a bolus then anyway and doesn’t lead to any lack of coverage.
If I wake up really late for my morning shot then my BG will have gone up, and even with the alarm I will occasionally forget my evening insulin, so it isn’t foolproof. Which is why I’m very curious to try Tresiba. My first endo appt in several years will be next week now, and I have a pretty long list of things to get (CGM, Tresiba, Fiasp, Afrezza, … anything else I should add) 