Noun '---ING' is always uncountable?

[peppy_man]

Is a noun ending with '---ING' always uncountable?

Is there any exception?

eg. Grade skipping allows talented students to fulfill their potential.

Smoking harms our body.

[Casiopea]

In -ing, to my knowledge, yes. Gerunds are singular nouns:

EX: Swimming is . . . => It is . . .

In -ings, no. Some nouns ending in -ing are not gerunds. They take plural -s,

EX: The cake trimming is . . . => It is . . .
EX: The tree trimmings are . . . => They are . . .