OP:
You might need a different saddle. Specialized makes many good models, many of them in different widths, and their dealers can measure your sitbones and make recommendations.
You might also need good shorts (or bibshorts) which fit properly.
You might also need to shift your position around occasionally. I like a saddle that allows me to scoot a little fore or aft, as slight shifting of the load will help on long rides.
But, to answer your question: with the wrong saddle, my posterior might start to ache after 20 miles; with the right saddle (and all other variables dialed in) I have ridden 200+ miles in a day with absolutely no issues.