Routines are helpful for everyone, not just toddlers.
Every night before I go upstairs to get ready for bed I run through the same steps. I check that the garage door is closed. I turn on the night light in the kitchen. I checked the deadbolt on the front door. And I press the lock button on my key fob and watch for the lights to flash once. If I forget any of those steps, except the night light, I will have to get out of bed to make sure it's taken care of so I can get a good night's sleep.
Another routine I follow to the letter takes place after I park at work. I get out of the car and walk around the back, checking the windows are closed as I go (obviously not a huge concern in November). I make sure I've pulled through the spot far enough, I check the car seat, grab my bags from the front seat, and walk away, locking the car with my key fob as I go. I even have a little chant as I circle the car: closed, closed, clear, no baby, closed, and lock. I do this every day, even if it means I miss the shuttle bus. Even if people sitting in their cars are watching me. Because then I can get on the shuttle bus with peace of mind. I don't need anything else to worry about.
My son's bedtime routine is pretty standard. After watching a few minutes of Jeopardy, we head upstairs to brush his teeth (while watching an Elmo video), then we change his diaper, put on jammies, and read books (usually five). Then he nurses and goes to bed.
Mini routines help us get out the door in the morning before work, too. Our mornings follow the same structure day after day, which helps me get to work on time and helps him to know what comes next.
I'm sure most people incorporate routines into their lives, even if they're not as entrenched as mine.