Typically there's a separate connection but the pipe in the wall is shared, there isn't an entire separate pipe running all the way back to the heater, second set of holes through allstuds/joists, twice as much material, etc., never seen that. That's why they're on a shared wall or near commonly.

You run the hot in the sink near the washer, to replace the room temp pipe water with hot, doesn't matter if washer's directly connected, once hot comes from the sink, the pipe's filled too.

It matters even more with newer washers that use less water as a greater proportion is what was in the pipe versus gets there from the tank.

You can also tell by opening the washer door as it fills, it'll be hotter then.