How much endurance does it take to convert a 2:05 800m to a 15:00 5K?

That’s interesting thanks will try that work out as you said the 1000m reps would work better for 5k race, I have only run one 3k not an event I do that much and I did 8.59 which was not great, I think half the trouble is thinking I have to do 7.5 laps or 12.5 laps rather than just switching of, but when I do that the intensity just drops. I know im cable of going faster but its just putting it together that’s tough

I ran that 3k indoors on a 290m track so it was something like 11-12 laps. I remember feeling comfortable through 2:19 at 800m and starting to go a little numb at 3:29 for 1200m but I was still feeling strong. I was out a little fast though and ran a little bit slower through the middle but never really died and finished with 8:58. My goal was sub 9 so I was pretty happy with that.

In the 5k which was about 2 months later I was running 72-73s through 2k and didn't feel too bad but I did not quite have the strength to stay on the pace for a full 5k. I got gapped by the first group and was all alone in a somewhat gusty wind until 800m to go when I caught 2-3 guys who died from the front group. I was definitely in sub 15:30 shape then and if I had a day as good as the day I ran 8:58 I would have been around 15:20. I don't think my workouts were as effective then as they were during that indoor season. I was doing 5 x 1000 in 2:55 but with 400m jogging rest. I didn't feel as strong in the middle of races. Probably would have been better off with 5 x 1000 at 3:05 with 200m rest...

I'm surprised you've run sub 70 for the half and not run faster at 5k...

The 69 was off the back of cross country training just at the end of the season but when it comes to 5k I shorten my workouts and base them more on speed so I seem to be able to nock out an ok 800 but just don’t have the speed for the 5k I seem to get gaped pretty quick in races from people running 15 20 pace which is irritating because I can usually beat them over the country I think your right about the recovery for 1000m if you keep the intensity up with little rest what you lose in time by doing 3.00 instead of 2.55 you make up for in a race with the strength to be able to continue it to the end, i will need to re do some of my session I think