Conditional Custom Format

I knew that Custom Format syntax consists of 4 blocks:

Positive;Negative;Zero;Text

But I didn’t know it can also recognize conditions¹:

[condition 1]custom format 1;[condition 2]custom format 2;other number format;text format

See example² from the GIF:

[=1]0 "day";[>1]0 "days"

Source:

1. https://stackoverflow.com/a/47784280
2. https://office-watch.com/2022/singular-plural-text-in-excel/