I can only answer from personal experience.
I am a fat guy and I have found that my rear tire will walk backwards on my rim with anything less than the max pressure,65psi.
If you are a skinny guy and don't ride your bike hard like i do, then i can't imagine it would matter.
I've never had a problem with overheating/over pressuring. I have never blown the bead off of a rim that it fit, and I've run sketchy tires & and antiquated equipment.
~50# works for me on most tires, but I'll take comfort over speed.
The more air you have the less the road resistance but the harder the ride, kind of like solid tires, not a smooth ride without shocks.
Your MAX is more a suggestion. If you have modern clincher rims and a wire bead there is no reason you can't fill them to 100psi. The 700x18 I have on my road racing Giant TCR Zero has Michelin Dynamic sports at 120psi. on my MB I am using Specialized Nimbus Flak Jackets (26x1.5) at 80psi. Low pressure makes the sidewall roll more and causes extra wear. It also causes more heat and friction and can have negative effect on handling. I've only had one tire fail from high pressure and it was the sidewall of a continental ultra sport. That was from age tho, I got it second hand and didn't look it over very well.