Question on swim training for 70.3

The primary reason you don't train in swimming like you do in running or cycling is the dependence on form in swimming, and how that breaks down so easily when you're fatigued.  Learning to swim like 10 x 100 with 10-15 seconds rest where those 100s have great form and maybe a little quicker than race pace is better than training a 1K at the race pace.

That said, in one of my swim workouts a week I do a "cold" 1K warm up with a small pull buoy building very quickly to race pace to get a consistent feel for swimming hard without a long warm up, and the buoy gives me the buoyancy of my wetsuit (sorta).  Otherwise my longest non-warm-up interval is a 200.  I do sprints and Olys, nothing longer.

I think a bunch of long distance tri plans advocate for 1 or 2 long interval sessions like 3 x 1K or something like that, but that just sounds horrible in a pool.  If you've NEVER done a long swim maybe it's worth doing something long non-stop - I think my longest pool interval was a 2,000 yard interval for just that purpose when I was starting out and as an adult-onset swimmer that's probably a little more important.