Endurance athletes are often familiar with the concept of LSD- Long Slow Distance.
Swimming training for triathlons definitely requires some LSD training. But how long and how much?
Partly it will depend on the distance of your race. At minimum, I recommend swimming the distance of your race straight at least once per week (after of course you have mastered your technique!). Even better if you can swim in the open water once a week, but a long swim in the pool will be sufficient when it’s not feasible to get out in your nearest body of water.
When you do a long swim, make sure to include some stroke technique focus, flip turns, and stroke counting. However, remember to only focus on one thing at a time!