Using a decent pair of bibs?
I have found any on the Ciovita shorts are great for around 6 months, makes no difference between the high end or low end ones, the chamois all last around 6 months. after that i start getting sore sit bones. i have 3 sets in rotation doing +- 8-10hours a week.
love Ciovita tops. but the bibs are a no go.
I since switched to Assos. a year down the line again with 3 bibs in rotation and my ass is still very comfortable.
Saddle is also a big part, i used to like the Spez Romin saddle, but after riding a Bontager Aeolus Saddle i swapped everything to Aeolus.
absolutely love that saddle.