Your "average" 4 cylinder'd car (per your examples) rev higher than 6k before redline and the 5.0L don't even do that. It is around 5,600 rpm or so right...but starts cutting off even before then. Those toyota's usually are around the 6,500 rpm mark or so on "average". Plus the cars your talking about...they are usually newer and do they have the same rotating weight as a 5.0L for example? same valvetrain? same car weight? same need? same piston rings? same pistons? etc. Just a few...
I wouldn't idle my car around (not enough oil coverage). Bad example there