I find in my usage that creating a card can take several minutes (5-10 for a hard card) but reviewing them takes a few seconds per occurrence. To reach the initial creation time would take me decades of reviews.

That said, I still make all my cards myself and some cards are trivial. For the trivial cards, review time can outweigh creation time. But trivial cards take seconds.

Crafting effective prompts is important to getting the value out of an SRS. That sometimes is the bull of the "work". Not the review.