I consider under inflating the tyre is a no... no, in every aspect. You’ll loose fuel efficiency, more wear & tare on your tires, less performance, poor maneuverability, the only thing you get is better comfort. If you want comfort above all of the above points, then have a slightly less Psi on your tires.
According to some, Maximum tyre pressure - 10% is the best in economy & performance. (i.e. If your tyre indicates the maximum recommended tyre pressure as 40psi, then 40-10% = 36psi) Ya… in CMB roads it may be too rugged. I used to air them to 29-30. But since then I got a new pair of rubber, I do a 32 all around. Slightly hard but not too much I would say. I’ve tested with a tankful for the new economy. Definitely better than it used to be. Not enough evidence to prove it though. I think the new set of tyre has a lot in that increase as well.