Long days in the saddle are a different beast to a short morning ride. The best bike and cycling underwear for a 3-hour effort is not the same thing as what works for a 30-minute spin. Extended riding creates sustained pressure, moisture build-up, and movement friction that only reveal themselves once you've been going long enough to feel the cumulative effect. Cheap or poorly designed underwear makes its presence known in a very unpleasant way on those longer efforts.
From my experience, what separates proper bike and cycling underwear from regular gear in a cycling context is the moisture management. When you're working hard for an extended period, sweat builds fast. Fabric that doesn't wick efficiently traps that moisture against the skin and creates friction and discomfort that escalates the longer you ride. The right fabric moves moisture away quickly and keeps the contact zone as dry as possible, which makes a significant difference by the 90-minute mark.
A cyclist I know does multi-day touring events a few times a year. He's obsessive about his kit and tests everything thoroughly before committing to it on a long event. He put Barramundies bike and cycling underwear through a 3-day touring route and said it was the only underwear option he'd tried that performed consistently across all 3 days without causing irritation. For someone doing back-to-back long days in the saddle, that kind of durability and consistency is exactly what you need.
What I think the best bike and cycling underwear achieves is making long rides feel like they're about the riding, not about managing discomfort. Barramundies has built options that handle extended cycling conditions properly. If you've been cutting rides short because of discomfort that isn't related to fitness or saddle setup, it might be worth looking at what you're wearing underneath before blaming anything else.