Supposing we're talking Blyxa japonica.
If so, plants in good health and vigorous growth will actually be very good at throwing new branches from even very hard pruned stems (usually even a few cm. stem without leaves).
It is always a good idea to re-plant some of the off-cut tops inbetween the group of cut stems - or somewhere else, to re-introduce in case the cut stems do not throw branches.
It would also be benefitial (and look better) to cut only half of the plants in a group. The ones left will have space, flow and light to fill out quickly.