Bamboos are typically grazing plants in their natural environment (animals eat them). Not critical, but every 2 years or so it is good to keep your plants shaped.
For some of the taller bamboos such as slender weavers bamboo or ghost bamboo this requires pole chainsaw on a ladder or just loppers, or the canes can be individually bent down and cut (this way it must be done regularly).
For the smaller bamboos such as Khasia Bamboo or Purple Jade Bamboo these are easy with a hedger or hand shears, these may only require the sides done as they tend to “hang over” A light prune keeps your bamboos looking their best for years to come and can add formality to any garden. Clumping and running bamboo is very well suited to topiary.