I'm an old man (79 y.o.) but I've worked up to 50-60 mile rides. This is a mere warmup for those who ride 100 miles or much more. In my rides around town I can live with most any arrangement of the bike but after several hours, minor discomforts become major pains. At present, my bike is very comfortable even after 4 hours in the saddle but this was not always so. After the initial fitting from the bike shop, I did much tweaking over several years. I found, for me anyway, that seemingly minor adjustments caused major fit issues as I did the longer rides. So don't get discouraged if the rides get uncomfortable as your rides get longer. You will adjust the bike but also your body will adjust to riding.
Bern