And as for maximum speed? its egregiously avoided at all costs because it burns much more fuel than a slow lope across the globe. It taxes engines and in turn drives up maintenance costs.
"Egregiously avoided?" More like "avoided to avoid damage to the aircraft" You don't fly at max speed.
Velocity Never Exceed (Vne) is the maximum speed of an aircraft - and no one stays there for long at all. If you stay there too long or go beyond that, very bad things likely will happen.
All aircraft have a cruise setting, which is some ways away from Vne.