I used to swim a mile daily. No HIIT swimming, just a fairly efficient mile with friends. Not for weight (my weight is fine), but just for daily exercise, as much mental as physical.
In line with the Maggie's fitness program, I only swim twice weekly now, with HIIT laps as my pure cardio days. One sprint per 2 laps. Weights and calisthenics on other days.
Why we swim