>24 hour subway leaves no time at all to do any maintenance. I can guarantee you that they do maintenance 24/7. Having a break in service at night might help,

>24 hour subway leaves no time at all to do any maintenance. I can guarantee you that they do maintenance 24/7. Having a break in service at night might help, but the idea that a system can complete all the required maintenance in a 3 hour window in the middle of the night is a bit silly. Many repairs take longer than that.