Let me first begin by saying "I have been looking over the parses for quite some time"

Lightwell Usage in our 25 man is a Complete "Zero" in a 8 min fight on Cho'gal we had 3 clicks on it total....

Ummmmmm Not ok.... So let me Educate you on some Specifics of lightwell usage.....

From MMO-Champion
– there seems to be some concern regarding the Lightwell mechanic. So
in the interest of educating myself and the one or two others who might
be reading this, here’s some info.

• It is the highest heal-per-mana (hpm) spell for priests.
• You can click it from up to 20 yards away.
• Clicking it will not change your target and does not trigger the global cooldown.
• It heals for more per tick than Renew.
• It can be used while stunned, disoriented, sapped, blinded or casting.

WoWhead’s description:

• Lightwell
• 30% of base mana
• 40 yd range
• 0.5 sec cast
• 3 min cooldown
• Creates a Holy Lightwell.  Friendly players can click the Lightwell
  to restore (((2878 + ($SP * .308)) * 3) * 1.25) health over 6 sec. 
  Attacks done to you equal to 30% of your total health will cancel the
  effect. Lightwell lasts for 3 min or 10 charges.
• You can click it from up to 20 yards away.

From a comment on that page:

This spell is way more powerful then you all think.  This spell can be used while

• Tanking
• Kiting
• Blinded
• Stunned
• Disoriented
• Sapped
• Casting another heal or spell
• You can click it from up to 20 yards away.

You don’t even need to un-click your current target. Lets compare with a more favored heal over time, Such as Renew.

Lightwell costs 30% of base mana, and does 10charges or “casts”.

So really its 3% of your base mana for every charge.

(the following is at 290 spell power)

Each charge heals 10,000 over 6seconds.

As for renew its 6,124 over 12seconds and costing 18% more mana per cast (compared to each charge)

You can literally be in two places at once, having your light well
positioned properly. Heal ranged dps, or yourself while your to busy
focusing on people who are dieing rather then injured. The ticks also
tick faster [down from over 6seconds] with your haste. All you have to
do is, Click.. and we will be well on our way to appreciating this
spell.

Let me help you even more......

Here is a two part macro for using the lightwell and you don't even have you move your face from Cho'gals ass

I would suggest using the following link as it explains setting up a "No Click" lightwell macro

http://harpysnest.wordpress.com/2010/10/17/lightwell-and-loving-it/

So in closing I will make a deal with you - I will keep that sucker down and on cooldown but please don't make me regret even having the talent point