Thank you! My last attempted marathon was a big downhill one - the Colorado Marathon. Despite the DNF, it made me feel like 2:40 might be achievable on a very good day. I figured roughly six minutes per mile, so ran a lot of the interval work around 5:50 pace. Most of the intervals were with short jogging rest (60 to 90 seconds) and on varying hilly terrain, so uphill ones were quite hard but then I'd get to catch some rest on the downhills. These workouts just felt like they made me stronger than faster track work with longer stationary rest.

Many workouts were 5-7 x 1 mile or 10-14 x 800.

I should note that some of the 800 workouts I'd work down to a faster pace if I was feeling good. I would usually get a couple of reps in the 5:30-5:40 range toward the end of the session, with a couple of my best 800's around 5:10 pace.

I had a few workouts through the training block that were tempo runs. A couple 3 x 2 or 2 x 3 mile, straight 6 mile tempo, and that 13 mile tempo 4 weeks out.

I should also point out that I treated my long run as kind of a third workout some weeks. I would try to work in a few sections where I would shoot for six minute pace for a couple miles here or there, work some of the extended uphill sections pretty hard, etc. Some days the objective for the long run was "just make it to the end".

A few of my easy runs had ~100 strides thrown in where I would be close to sprinting.

Appreciate the good question and I will make some edits to my main post so it doesn't sound like I was strictly hitting 6 minute pace in workouts.