Personally, I don't think you could ever have "too many" links from one source. Its definitely not going to hurt you, but it might not carry as much weight or authority as just a few from the same source. We all know that whatever tactic you use to build backlinks - CONSISTENCY IS KEY! As long as its working for you. If it's not, then by all means, move on and find something that will. Once you do find something, make sure that you now add a little variety to your consistency of link building. And I know that Article Marketing is by far one of the Best Link Building Techniques out there.
if your website having lots of links from the same resource then all are the waste for us, there is no need for lots of liks from a single source for SEO purpose you have to prepare back links from the different sources...
If from different pages it could be effective. But I beleive much effective to deversify your list of forums. Post many only on the niche forums. Use forums with different PR.