coaster brakes on/in the mountain biking field of play, that's not easy at all...it's tough to time how and when you'll use the brake.
ha ha ha... back in the day when all BMX bikes where rocking nothing but coaster brakes, we used to use household lubes for the coaster brake.. pack the hub filled with whatever we could find. on this really steep and long hill near our house, we roll that hill, gently riding the brake the whole way down... with some of the lubes, the hubs would get so hot, they'd melt the lube or even start to smoke cause of all the friction. I think there was even a time where the hub burst into flames cause the lube (butter) we used was flammable *** I was a pyro back then so maybe it was cause we poured gas on it (?). chuckle...our big thing was going as fast as we could down those hills, slam on the brake to see who could lay the longest skid without popping the tire OR the ol' set the wheels on fire trick, that's kinda cool... kids don't try this at home