OK - I don't know if I could really have six, but I could easily support three. One of the recurring questions to Blizzard is when will you allow tri-specs? I can see the appeal of the question, after all I think the dual spec system has been a fantastic addition to the game, but where would you draw the line? Also, when did the cost go to 10g, I really want to know that one.
As a Paladin we have three distinct builds that we can play. Holy, Prot, and Ret. While I leveled with a Holy and a Prot set, now that I'm down and dirty with raiding, I run with two different Holy builds - much like our Prot pally has two different tank specs, and I think our Retadin even picked up a build without Eye for an Eye just for tanking Chimaeron.
Who owns your second spec?
With a second spec runing you a measly 10g now, the question comes up as to who controls your second spec? Is it reasonable for your guild to expect that you maintain two different builds for handling different encounters? Should hybrids be expected to maintain an offset just because they can? Those are questions each guild and player will have to answer for themselves.
The availability of large and diverse builds kind of went away with the new talent system. Requiring 31 points in your primary tree really limits your flexibility, but I don't think this is a bad thing. The talents are already confusing if you don't know what you're looking for, and doubly so if you haven't done a lot of research. Do you put points in Blessed Life? Is 2/2 Eternal Glory needed?
For everyday healing, I run with a 31/5/5 build. 1/2 in Last Word, and 1/2 in Enlightened Judgements. Last Word is a talent that is just filler for most situations. A crit is nice, but odds are good that if your target is sub 35%, you're going to be rocking a lot of other stuff in their direction. Enlightened Judgements is unneccasry after 1 point - you'll have more than enough hit if you aren't gimping your Spirit. If you are gimping your Spirit, well that's another post.
For H-Chimaeron I run this build. This is more like a Shockadin setup, but without Blessed Life and Eternal Glory. In my logs I've found that over an average Chimaeron fight I'll get about 12 HP from BL and EG each. While that's 24 free HP, I need the DPS output in P3, and AM buys a few extra seconds for everyone else. This also lets me pump out some DPS on H-Halfus.
Those are my two 'standard' builds, but I'd certainly play with more. Builds that had cleanse and don't, some with Blessed Life, others with PoJ. I'd go crazy!
I could fill up every available spec with some variant of a Holy build I'm sure. If we had unlimited specs, well then sure, I'd suddenly have 15 different combinations of PvE/PvP Ret/Holy/Prot builds, probably just because I could. There's certainly nothing wrong with just using a basic cookie cutter build either. I haven't found a fight yet that I 'had' to spec out of that for, it's just convenient.