We didn’t have it for private school nor for the private U for either kid. There was one term that D crashed and burned where it MIGHT have applied but D never told us or anyone until it was too late anyway. We paid and her grades were horrible. She took an extra year to graduate due to sequencing of courses.
I’d say read the fine print. Generally it’s a hundred or few hundred vs 10 to 10s of thousands, and should be seriously considered.