The answer is, “It depends.”
The number of holes in salt and pepper shakers varies by culture, health, and taste.
Here in the US excessive salt is considered bad for you, so the salt shaker is the one with the fewer holes, but in parts of Europe, it’s the other way around.
It also has to do with availability – in some places salt was rare and prized, whereas in Europe it was difficult to get your hands on Pepper since it’s a spice from the Orient (very exotic) which was used to spice up meat that was past its prime.
Another factor is the size of the grains – some salts are quite coarse while others are very fine – and pepper can be ground or it can be cracked, which many cooks prefer. So, what will pour better?
Exceptions abound – you can have 1, 2, 3 or more holes in a shaker, and they go from tiny holes to huge ones.
In the end, everybody wins! The next time you shop for a salt and pepper shaker set, just buy according to your taste – practical or whimsical – and fill them as you wish. Enjoy!