Opinions on Time vs distance

what plan are you using?  I haven't seen a plan that states "swim 400 yards in 12 minutes"  They would usually state either swim 400 yards OR state to swim 12 mins.

What did you do for the other 8 minutes?  Was the the entire work-out?  To make a judgement on what I would do, I would have to see the entire work-out. 

With swim workouts like this, it's usually the distance that's the goal,  assuming a certain level of ability. The time is a general idea of how long you should be in the pool, not necessarily how long it should take you to swim the 400.

Below is the workout description, note that it mentions rests between lengths. The 12 minutes is a guideline for someone who doesn't do it as one continuous swim. Even then, it's a guideline. The goal is the distance.

Swim Drills Day. Today your only goal is to get in the water and count how many strokes it takes you to swim from one of the pool to the next.

Focus on keeping your head down and turning, but not lifting your head to breathe. Take a rest of no more than 1 minutes between lengths.

If you can try to swim continuously even if you have to swim side stroke, breast stroke, or on your back.

Keep moving and complete 400 yards or 1/4 of a mile!

When you are done swimming, work on stretching your back, your arms, shoulders and neck muscles.

Virtually all, if not all of the BT training programs will give you a specific swim workout and a time for that workout.  I've always just focused on the workout and paid little attention to the estimated time.  Sometimes I get the swim done quicker than the time estimate and sometimes longer.  Either way, just do the workout and you'll be fine.

Click on the "Programs" link at the top of the BT page.  Some of the basic programs are free and the more advanced programs require various levels of premium memberships.

Swim is by distance.  Run and bike is by time.  That's how I do it.  And the BT plan is consistent with that.  The plan I use only gives time as a goal for r/b but both for swim.  I think they provide a time with the distance for a swim to estimate the weekly time and to assist in scheduling your workout.  I am faster than the estimated swim time 99% of the time.

I talked to the plan author, and he stressed it was important to be running/biking for the time, and not worry about pace or distance (as long as you are working at the correct intensity).

The reason a lot of people DON'T use time as a goal for a swim is because many swim workout have rest intervals and breaks that run/bikes don't have.

just my 0.02

That workout is from the Winter Maintenance/Prep - 4 to 7 Hours - 20 Week plan which is available with a Silver or Gold membership. You can see the details of the first two weeks to get an idea of what the plan entails.

Remember, that those memberships get you access to our whole library of training plans, not just one plan.

You are correct Marmadaddy!!  Except I modified my plan to run 5 times a week.  Running is my weakness!!!  I plan on following everything in that plan except the running times.  The 10 minute runs in that plan will be 30 minute tready runs for me.  When the plan calls for an increase in time for running I will go beyond the 30 minutes. 

 I only asked about the swimming because swimming is my strongest sport and I felt guilty like I was slacking off after 400 yds even though thats what the plan called for.