It comes down to tactics.

One simple one was to have the archers at the back of your ranks. When the enemy was at a distance, the archers could fire volleys in a high arc over the heads of your soldiers to rain down on the enemy soldiers. Then, when the armies got close enough for hand-to-hand combat the archers would be taking pot shots here and there.

Another one was to put your archers on high ground like a hilltop or castle tower. That way they could fire over the heads of your soldiers and into enemy ranks even at closer ranges.

Archers were also considered "efficient" in terms of speed, for a little while. In Europe, from the 14th to 16th century, crossbows became the ranged weapon of choice in some armies, because soldiers could fire a crossbow more accurately with less training. However, that particular "efficiency" of the crossbow came at the expense of speed and quantity. In the time it took a crossbowman to fire a shot, reload, aim and fire a second shot, a bowman could fire 4 or 5 shots. And, provided you had a good supply of the right kind of wood, you could build a lot of bows for cheaper than crossbows. Meaning, you would have more men firing more arrows.

And yes, it was typical for an army to have hundreds or even thousands of arrows made in advance, with each archer typically carrying about 2 dozen at a time. And at the end of a battle they could retrieve shot arrows from the battlefield.