At judo yesterday, I did eight mini-rounds of newaza randori and two normal standing rounds. That's 22 minutes of randori, which is a lot for me.
I searched for "randori" in my old blog and found this:
2008-01-18 02:21:30
Hey! Guess what? I'm finally in shape! By which I mean I have a level of conditioning that satisfies me. Tonight at judo, I did five rounds of tachiwaza randori and five five rounds of tachiwaza randori and five rounds of newaza randori, with about one and a half breaks. That's fifty minutes of sparring, broken up by seven minutes of break! It wasn't necessarily tournament-level fight for-your-life randori, and plenty of people have done more, but for me, that's a personal endurance best. There have been times when I've had trouble going two-in-row.
My technique has gotten a little better than it was then, but I don't think fifty minutes of sparring is ever going to happen again for me. Enjoy your thirties if you have them, people.