Generally, probably 95% of the time. But I do check around to see if I missed an item when scanning the sales online, and if it's something we'll use, I buy that as well.
Starbucks...ugh. I used to stop there regularly on the way to the train, but I missed too many trains because someone ahead of me was putting more thought into their grande mocha-smoka-latte-chino purchase than I did when I bought my house. At 5.30AM, the coffee order should be simple, or at least know what you want and don't try to learn the menu.
I made mine at home for a while after I stopped with Starbucks, but then Speedway opened a station near my house. I like their Colombian Blend and at 5.30AM, at this location at least, it was mostly trades-people and they didn't have time to peruse the menu or chat up the clerk. I was able to get in and out fast enough to make up for the fact that the station was a bit out of my way and always made my train.