I was an awesome swimmer back in the day. From all the sports i've done, i think the only one i was gifted was swimming. Kept winning all the races too, and with that attitude before starting that 'no way i'm not winning, i am the best by far'. Unfortunately (or not) my parents cut me off early, we had a close relative that was Olympic level and his parents said that it requires too much time and effort and there is no actual reward. Whatever!
Anyway, one really cool workout for distance swimming that i got from a coach once was this: Start every new 50m every minute. If you want to do a WR 25s and then rest 35s , it is fine. If you want to do it in 59s and rest 1s it is also fine. But every minute you must start your next 50m. Something like EMOTM? lol That also helped a lot to not lose track of the distance covered, there were no fitness trackers back then, but with this method you know that you will be doing 500m every 10 minutes. Also allows you to AREG, make it 'LISS' or "HIIT' or fartlek or whatever. Really loved that workout style.
2c.