not sure if this suggestion will help since i only ran on treadmill.

But i managed to improve my 5k time (0 incline) to 22 minutes 31 seconds within about 4 months of adding jogging alongside my usual gym routine. Not sure if this is good or not but I never performed any sort of cardio during the past 4 years when i started going to the gym to hit the weights.

All i did was simply performed interval between 12kmh, 10kmh, 15.5 kmh. Each session i will try to increase the duration of the 15.5 kmh by at least 30 seconds to 1 minute.

The 12 kmh was also crucial as that will ensure that the 1 km time is at 5 minutes. The goal at that time was 5km max should be 25 minutes.

The 10kmh, as you had guess it, speed for after the 15.5 kmh attack. The shorter the duration, the better obviously.

I started things rather haphazardly. I initially only ran for 15 minutes and not worrying too much about the distance covered.

After that I gradually increase the duration to 20 and then 25 minutes. Only after i hit 25 minutes (and still not bothering too much about the distance), i started to seriously see if i can tackle 5 km in 25 minutes and reduced it slowly.

5 km in 25 minutes didn't take me that long iirc, probably slightly more than a month. But reducing the time from 25 minutes to 22:30 did take a while. I only hit that time only once and then just consistently maintained at 23 minutes ish for 5 km.

on occasion, usually on sunday, ill try to hit 7-9km and managed to hit 10 km in 48 minutes once. Though i noticed the better i run, my strength in the weight room was also declining. So i stopped running altogether since endurance was never the goal