I don't think there is any such thing as too many hubs. It just depends on the quality of the hubs. If they are poorly written, then it isn't a good idea to create so many. If you can write 2 or 3 hubs a day and they're all good, I say go for it.
Sometimes I write a few in a day, but if I know I won't have time to write any for a while, I will wait and publish a hub a day or a hub every other day.
I suspect with some hubbers, they already have articles written and that is why they have so many to post on this site in a short period of time. Some people get feed up with other sites and remove all their articles to put them on this site.