What happens if I take too much rest on a workout?

You'll be able to do a higher quantity of reps. If you keep the number of reps the same, you'll get less good at holding that pace for 10+ miles when you race. You might recover slightly faster.

But look, most workout plans are not science. If you feel like you need 3 mins between reps at threshold pace, you should probably take it. But you should figure out why the original plan isn't working - was it overambitious? Are you approaching overtraining?

You may end up overcooking the pace on the reps and running too fast to recover properly even with the extra rest.

Extending rest is fine every now and then if you're having an off day or feeling fatigued from the week, but shouldn't need to do it for every workout

Slow the pace a bit, so you only need 90 secs.

Overall it will be less taxing. Muscle tension won’t be as low. Feel less aerobic letting your heart rate drop more. The key being to make sure your pace is at threshold and not going faster do to more rest. If your dealing with the summer heat it can definitely help.

You have to go back and start the workout over again. Otherwise it doesn’t count. Those are the rules

From my understanding, the highest percentage of recovery takes places in the first 30 sec. So, if you take too long between reps you might not get the same stimulus.

Standing rest of jogging rest? I do 90 seconds rest for threshold 800s standing rest in hot weather.

If you really need three minutes rest, then you're either not running at threshold or you haven't warmed up sufficiently or both.

you'll run reps faster. if you already race a lot, you're fine. if you don't race a lot, you'll get better adaptations to race conditions by taking shorter rest.

who really knows. probably as much bro science in running as lifting. as long as you're progressing something (speed, no of reps, length of rest), you're getting better

3 minutes is probably an efficient use of your time if you're REALLY at threshold

You could get arrested by the LRC police department.

Why does it have 90 seconds? Three minutes with faster paces is just as good a workout.

No that's only if you forgot to start your watch

Personally I take multiple days in-between reps. Workout is 20x400. So far I have averaged under 60 seconds for each 400. But I can't break 4 minutes in the mile yet

You will evaporate.

The OP is doing mile repeats as a threshold session. It doesn’t have to be 90 secs, it could be 60 secs, etc.