The right way to gradually prune nandina back is to cut a few of the tallest, oldest canes back to the ground each season, leaving shorter canes in place that will continue to produce carbohydrates, helping to rejuvenate the plant. Cutting everything off in one pruning means that all of the recovery effort would be fed from carbohydrates stored in the roots, making for a weaker recovery. More shoots should come from the ground each season if the plants are in healthy condition.
hortster

Yes, a cane grower renewing itself via new canes from the root crown. Maintain by cutting out oldest, tallest floppiest canes once per year (or less often), leaving the rest to continue the cycle.