also, some strains (romulan) HAVE to be topped. romulan, for example, grows a huge main cola, it often gets so thick, that by the time the outside of it is ready, the inside gets moldy. topping a romulan plant will give you several colas that are less thick than the main cola would've been without topping, helping avoid mold.

this tip came from a grower i know who's been doingthis for a long time.