New to animation - how many blend weights can I have?

I understand you can only have 4 bones affecting any one vertex, or so I've read... How many blend weights can you have? Do these operate on completely different principles and therefore they're unlimited or is there a set number one can use?

I just would like to know before I make any complex models and find out I've wasted hours getting the perfect rig w/ blend weights...

 

I saw a screen shot of the unity editor with a setup of a character being effected by 10+ morphs (blend shapes) at the same time. I can't remember where I saw it but I do recall seeing it.
You said blend weights - so if were not talking about the same thing I apologize for the confusion.

I have actually experienced bad skin binding/weights in Unity when there were more than 4 bones effecting vertices. I had a unfriendly rig with 3 twist bones in the wrist. I reduced the twist bones and cleaned up the weighting info and the skin weighting ended up accurate in Unity.

 

Sorry, I meant blendshapes... And, yes, that's what I meant. What would you need three twist bones in a wrist for?

 

Ha! Absolutely nothing - The default biped setup in Max at that time generated 3 twist bones on creation of the biped, and I wasn't very experienced with Unity animation pipeline then, so I just used the default setup. Thankfully I was able to deduce the problem pretty quickly. But - man those wrists/forearms rotated like flesh butter before fixing the rig correctly!

Did you see the Unity 5 blend shape/morph update?

 

No I didn't - I'll have to look at that... Got a link to what you're talking about? I don't have a blend shape model within easy reach to just experiment with (though I could make a cube or something I guess but I always end up cluttering my assets folder up with junk for testing)

 

http://unity3d.com/unity/whats-new/unity-5.0

In the animation section under Features.