Depends on space you want to fill with the plant. Stick to one vertical cola per 6in^2 and you'll do well. So if you need to fill 24x24, you'll need 16 well-spaced tops. I'd cut every other node, but depending on how things played out over time, the bottom line is filling the space with an even canopy. I'd also consider how many shoots are coming off one branch.. try to spread it out as evenly as possible.