I didn't break 01:20:00.
The race entry list was FULL. And I was in the second (fast) wave. Having missed the deadline to update my estimated swim time ( I wanted to make it slower due to technique confusion at the moment), I ended up with a few faster people behind me, which meant that I had to stop once to let one person past in the pool, then again to let two past, and again once more to let one more past. I probably lost 10-15s due to that.
T1 was quick - the guy after me in the start order who overtook me in the pool was probably a bit miffed that I came and went while he was still in transition before me and trotted out behind me.
The bike... well, it's not on closed roads, so there's always the luck of the traffic lights. I was lucky and they were green and I sailed through. However, I had to come to a complete stop at two of the roundabouts, the second of which was extremely frustrating as there was a car indicating left at the head of the traffic queue who was very hesitant so I had to wait around 10-15s for them to sort themselves out and then decide not to turn left in the end. A little way after that roundabout, I was stuck behind two cars, a learner at the front who was not happy to go at more than 20kph, with traffic coming the other way on a relatively narrow road, me and another race participant had to hang way back (non-drafting race, of course) for 400-500m of faffing. I probably lost another 20-30 seconds there overall and added a bunch of rage.
T2 was very nippy as my bike was near the bike in and run out. Heavy legs weren't too much bother, but a double stitch (one upper right abdomen, the other lower left) made me slow to a walk for a few paces to try to sort it out. I still put in a run+T2 time of a minute faster than ever before.
Overall, 01:20:57. 30s slower than last time. The run was encouraging, the bike very frustrating and the swim just annoying. I coulda done it. I coulda. But it didn't happen.