Fleece lined Tri-shorts

When racing / training in tri shorts or tri-suit, do you use a gel cover for more comfort or do you do the whole race in ie. bibs? I was wondering if the gel cover actually works, does it stay in one place or does it slip to the side and cause grievances.

I’m thinking of HIM and IM distance.

the desoto gel cover is great. it becomes part of your saddle and helps a lot with comfort in tri shorts on looong rides