I try it when I feel it.
I figured if I could do 20 miles on a Kaitai, then 25 on the Reno was a no-brainer.
Now, I've done that 3 times, finishing with varying degrees of "freshness"... sure, I'll try 30 sometime soon. I might even go for 50 by year's end but, no, this is only a competition with myself. I'm in no hurry. But I *will* continue to push myself.