I achieved a PB today by miscounting and doing an extra 2 lengths, so it was my longest ever swim at 3266m. The pacing was good too.
The moving average was 2:20min/100m with a the first set averaged at 2:18 and the last at 2:21. That seems very consistent to me. Consistency became easier as time passed as people left the pool for home (or a night out). Initially I had to adapt to others in the lane but by the time I finished the pool was empty apart from me.