In St Annes YMCA pool this morning I managed another PB without trying all that hard. It's only a 25m length so easy to shave a few seconds but managing 4:40 minutes for 200m is worth noting for me.
I also did a 100m set with bilateral breathing which was OK, a little collapse of leading arm and loss of high elbow, but a fair start. I'm not sure which set it was in my records so not clear on the pace, but that's not important. Across the whole session the pace was fine, although the recorded average pace is incorrectly low due to missed turns (the Garmin 935 isn't as good as the Swim for recording lengths).
I put a fair bit of effort into these short sets and was pleased to see that my pace was better than my estimated CSS suggesting that the CSS may be approximately right.