This week I've done a long set with every 3rd length aiming to be faster, and today, negative splits within 300m sets. There's been mixed success, today especially my pace was affected by others in the pool so hard to check the numbers exactly. At least the effort was there. I've also kept a set or two of bilateral breathing and today managed 100m with a few cheated extra breaths. That seemed manageable after 4 steady individual lengths with bilateral breathing. I still feel 'short of breath' as I did years ago and suspect I'll never break this sensation at this point in my life.
I'm generally satisfied with progress as I'm increasing average pace, distance per session and distance per week. Actually writing that down makes it sound like an injury risk. Let's hope not.