Often, the problem is the shape of the saddle. I tried four different models in an attempt to replace my original design Fizik Gobi (no longer made) and never did find a suitable replacement. The original Gobi design is quite round from side to side, while the majority of current saddles are much flatter at the center, with smaller radius corners. Those corners hit me in the wrong place.

I used each of the saddles for serveral weeks, not just a few rides.