I've got a buddy, he rides a heavy gravel/touring bike with chubby knobby tires that has a beefy rear rack with a large pannier bag, yet he only carries a single 20oz water bottle on his rides. I ask him what's in his pannier and he says spare lights, a wind breaker, and his tool kit. That's not that much gear for a 20L pannier bag.
The bike is so heavy and cumbersome, but he finds it comfortable so he rides it on both short and long rides, mostly on the road with occasional fire road. It's annoying for me to look at as well as ride with him because even my "heavy duty" gravel bike is so much lighter and faster than his bike. We once did a S24O bike camping trip - about 40 ish miles with one significant dirt climb to get to the campgrounds. My moving time was a generous 4 hours, but my total elapsed time was 6 hours because I literally had to wait 2 extra hours for him over the course of the ride. He also goes on these 50+ mile rides and spends all afternoon doing it, too. I cannot fathom how he can tolerate the slowness and inefficiency of doing those kind of miles on that bike, but he says he enjoys it. I told him if he wants to ride with me, he's gotta leave that bike at home and bring something lighter and quicker. He says I'm trying to be macho and that if I want to do a hustle roadie ride I should do it without him. I tell him I'm just on a regular road bike and that I'm not even pushing it, in fact I'm holding back just to not drop him on a coffee ride. Guy looks like he's touring when we're just going for coffee.