It depends on the hub’s subject matter.
If it’s on a subject that’s in the news and a new twists is reported I will add an up to date detail. Other times I may browse one of my hubs and catch some type Os or thoughts that weren’t as complete as I think they should be.
On average I would say I probably tweak one of my hubs every one to two months.
Most of my tweaking usually takes place the first day or two for editing purposes.