Ha, I'd say the opposite. IME I can ride on just about anything for 20 miles. It took me YEARS before I finally replaced the absolutely horrible stock saddle on my commuter (with one I pulled off the roadie), because I almost never ride it more than 20 miles. It's what happens when I'm in the saddle for longer that really tells.
As far as when enough is enough ... that's really personal. How bad does it get by the time your ride is over? Do you plan to start riding longer, so that you'll be experiencing more and more problems as the rides go on? Is the skin broken so that you have to spend time healing, or are you good to go by the next day? And cost/benefit analysis goes into the decisionmaking too, unfortunately ... saddle searching is expensive, so it definitely becomes a matter of "how bad do you want/need a new saddle."
Owlie is right ... you'll know you've found The One when you ARE floating on air after 200 km. Not all of us have found that saddle ... it may not even exist for all of us ... but that IS the ideal.
If you have an idea of a saddle you'd like to try, you might post a want ad here on TE. I think there are a number of TE'rs with saddles that didn't work out for them - or that are worn out but still usable enough for someone to get an idea about.
Last edited by OakLeaf; 05-12-2013 at 04:19 AM.
Speed comes from what you put behind you. - Judi Ketteler