When I was 14 months into retention/celibacy (now over 5½ years), there was a discussion of the brevity of orgasm, so I tried to imagine one to estimate its duration. To my surprise, I couldn't remember much (except that it somehow supposedly felt good; but I was in a fog as to whether that was before, during, or after the release of seed). It seemed like something I'd read about in books but had never experienced. I asked two long-time retentionists about this, and both confirmed that it's a fragile memory that fades if not refreshed periodically. That good, really. I still have frequent morning wood, so I feel that my male parts are "stored serviceable." I love my celibacy, though, so I expect it to be permanent.
You actually do lose size and you can lose the function of your lingam/ wand after a while. When you don't have sex for a long time you will also release quickly. When I lost my longest streak I couldn't last a minute. There was another RU-vidr who spoke about the time he wanted to have sex after a long streak. He had issues getting erect. There's some truth to the statement, "if you don't use it, you'll lose it."
I have the most erect morning wood i have ever had in my life. So idono about it getting any smaller. And as for how long you can last, who cares? Sex is for procreation and a baby will still get made wether you'r having sex for 10 sec vs 1 hour. Come to think of it isn't it better to release ASAP? Think of it from an evolutionary standpoint, or look at animals in wild. They usually blow after two thrusts lol.
Make sure your not arousing yourself by lustful thoughts. Don't worry if it still happens as long as your avoiding lust and intentional orgasm. Trust the journey and reap the benefits.