I agree totally with what has been posted already. It is both advisable and encouraged that you should edit your hubs regularly to keep them fresh.
To that end, last year I edited 20 of my oldest hubs and to measure the effect of the editing kept detailed stats using Google Analytics. The performance of almost all of the 20 hubs improved, some markedly so as a result of being edited.
I will be continuing to do this while trying to publish as many new hubs as I can. I would thoroughly recommend editing and updating any hubs that have not been edited in the last year.