@lina Few people know it but the reason for this is very simple. While zeroes are round, a 1 has a sharp corner and a hook that could get stuck and damage the insulation around the copper if you would completely fill the line with ones. Instead, sending some zeroes every now and then to flush any stuck „1“ before a clog can develop.

A 0 can be neatly pushed through the copper at high pressure without damaging the cable.

Now you know!