Ed, I am a fan of yours and thank you for sharing some of your running. I have been reading about your 2-3 hours runs with great interest. It took me awhile, several months to be able to do two hour runs almost daily. I moved on to three hour runs after a year. I was able to do three hour runs several times a week. I had a few set backs, but now am ready to start the process once again.
It does take time and as you, I have no limit on pacing I just run. I, also found that running slow at the start and at the end seems to work out just fine for me, too. I found myself running "hard" (of course hard is relative) about once every three weeks....no intention of doing so, just happens. I would want to "bust" out ...lol!
I did get stronger and after awhile of adapting it felt normal.
I am once again starting the process with added enthusiasm due to a set back from falling on the trails and breaking my hand. It was several months ago, though I still have a problem with it.
When I restarted the process I know now what to expect along the way. I do, however, keep the idea of joy in my runs at the forefront. I do not want to drag around during or afterwards. So I find a balance and it works for me. I do know it does take time, a year or more.
Thank you Ed!