I find the notion that paladins can have more than one effective healing style in Ulduar inane at best. Paladins are the least versatile healers with the fewest tools. As a result, they can be given the fewest types of healing roles in a typical Ulduar 25 man raid.
Everyone knows that a paladin excels at single-target healing throughput. However, in Ulduar there are few if any bosses that actually challenge the ability of a raid to deliver significant single-target throughput (maybe thorim when stacks are getting high?). Rather, the name of the game is aoe healing. Despite paladins' lack of aoe capabilities, a well played paladin can make a significant and often vital impact in heavy aoe damage situations.
The best use of a healing paladin (i.e. the use that generally means the paladin is pulling his or her weight and isn't a wasted raid slot) is to plug holes in aoe healing. Thanks to beacon (this will especially be true after 3.2) this is the way that healing paladins will fill a vital role in how a raid heals aoe dmg while alleviating the need to worry about your tank. Most aoe dmg (XT, Hodir, Mimiron) have both steady aoe dmg as well as elements of spike to them (for XT, whoever has light bomb; for Hodir, anyone caught under the falling ice; for Mimiron p2, whoever he's using his normal cannon ability on while that aoe fire thing is going). The paladin's role is to therefore anticipate sudden spikes among recipients of aoe dmg and to always have a holy shock ready to save someone's life in the event they can't wind up a HL or see that two people will require quick heals simultaneously. That being said, if your "style" of healing includes keeping the recipients of your healing targeted, you need to fix that or you don't stand a chance of being a good healing paladin. (get either a clique-type add-on or use mouse-over macros [i prefer the latter])
But don't tell people they can be effective by developing their own "style". If 75% of your healing is overhealing, you're a waste of space. If you're just HLing on the tank, you're probably overhealing 75% (see previous assessment). And if you're casting FoL for any reason other than topping people off when there's a break in the fight (or vezax but that's a glaring exception), you're probably beyond help.
As an aside, if aoe dmg is the only real dmg in ulduar that matters and you can anticipate when it is going to happen (usually you can) Divine Sacrifice is your best friend. Speaking from experience, give me a raid with 2-3 paladins with divine sacrifice and a paladin can solo heal hodir 10 hard mode.
There are spells that a pally has in their arsenal that, while not used nearly as often, are still useful. Examples being Lay on Hands, Hand of Sacrifice + Divine Shield combo, Aura Mastery, and so on. Stuff like that can't really be taught. Neither can things such as who to put your Beacon on, who to put your Sacred Shield on, whether you use Holy Shock a lot or not, what judgment to throw up, etc, because all of that is dependent on a lot of different factors.
Holy paladins have only three actual healing spells that they would use on a regular basis, yes. But those aren't the only tools that they can use in order to heal during a fight, and those other tools aren't things that you can just say "Use in X scenario". There's also the matter of training oneself to have a fast reaction time, or to know when you could possibly deviate from your target to heal someone else if you can tell you can get away with it and someone else needs the quick help.