A teacher is said to be fluent in asking questions if he can ask

A teacher is fluent in questioning when he can ask many meaningful questions within a fixed time.

Fluency combines both quantity and quality bounded by time.

Asking meaningful questions alone captures quality but ignores the fluency of number and speed.

Asking as many questions as possible values number without meaning or a time limit.

Asking the maximum number in a fixed time counts speed but drops the requirement of meaning.

In questioning skill, fluency is one component alongside probing and redirecting.