Though once you have been driving your manual for a while, you can get a feel for the speed from the engine sound and knowing what gear it’s in. Or even from the throttle level equilibrium is at and how much of an incline you’re driving on at that equilibrium. And probably also from just getting used to how fast things come at you at various speeds.

Not that I’d give up the speedo but checking it is more of a confirmation thing than a real lookup.