Feeling quite tired after a busy weekend, so I just decided to work on technique today and went back to my tumble turns. The biggest issue is timing, really. As my speed through the water increases so the point at which I initiate the turn must move further away from the wall. Getting that right is still tricky.
I ended up doing:
400m f/c warm-up
16 x 50m tumble turn practice
200m f/c swim down
USRPT distance this year: 39,900m
Total distance this year: 83,950m