At Paris-Brest-Paris in 2007 I had a 10 pm start time (I had been up since 8am that day). We rode straight thru until 1:30am the following day (27.5 hrs) to the sleep stop. That makes a total of 41.5 hours waking time. I have known many Randonneurs to ride thru a 600km event without stopping for a nap, finishing in 26 to 28 hours. I personally prefer to catch a 2 hour nap on a 600 km but many do not. My best time on a 600 km (with nap) is 30 hours. I have done a 300 mi event (the Grand Tour 300) in 21.5 hours but had a good group to ride with. I could not do that time and distance alone. I do not think that riding for more than 24 hours at a stretch would strike many distance riders as unusual.

You do not know what you are capable of until you try and push the limits past what you think you can do. I'm just saying that you might be capable of more than you think, and others are as well.