Get tires equipped with a Kevlar layer or comparable material. It makes a day and night difference in terms of frequency of flats. Yes, you will still need to reserve time for a flat, but the likelihood of a flat might drop to next to zero.
+1. I had one flat last year (why does saying that feel like the kiss of death?)
Typically my 1.5 hour comute time varies by a few minutes max. The variance among car drivers stuck in various incidents is way more than mine. A few times a year bunches of people will be delayed about 45 minutes.
I change tires slowly and carefully because I'm (thankfully) not practiced at it and because I want to find the leak and make a good repair. It's not hard to spend 20 minutes before I'm done and riding again. And because I remember Charlotte's good advice (never hurry, never worry).