Is healing supposed to be this...hard?

[Rein_eon_Osborne]

To the OP...
Like any other roles, it just takes time to get used to the gameplay. It is alright to start from 'overhealing' as you tread slowly to 'efficient healing'. One of the drawback in DF parties is we'll never know what kind of players we'll be matched with.
Sometimes it's the top-notch players: your mates won't be needing too much tending and you can DPS away (some oGCDs are sufficient).
Sometimes it's the decent/average players: your mates may hiccups a few times. DPS window from you is getting tighter but by no means, still possible. Just have to be more vigilant.
Sometimes they're just plain terrible: out of oGCDs and packs are still mowing down your tank, for whatever reason... could be tank blowing off all their cooldowns in one go, or simply forgetting them. Or one of the DPS sleeping. Or too much eating red carpets. Just try your best here. Add in your healing spell as long as your resources allows to. If it still leads to a wipe you should know it shouldn't be on you.

Adjust accordingly.

In regards to Clememecy usage...
To me, they are a signal to me to squeeze in more Glare/Broil/Malefic/Lightshow/Ground Slap/Gravity... only to some extent.
I would get annoyed if:
1. I slapped an Excogitation only for it to never proc because the PLD's too scared going below 50%. (I main SCH so this irritates me the most)
2. There's no incoming lethal damage but still insists to Clememecy self or other party members to full HP.
3. Clememecy'ing to the point of not giving me the chance to abuse Benediction's & Essential Dignity's powerful potencies.

At that point I'd look up to see if the said PLD ever played other healers. If they don't, I'd usually give them word of reassurance and encourage them to go wild with that Holy Spirit/Circle.
If they have healers leveled to 80, well... I'll just enjoy that Clemency animation... subjectively speaking, I love it. lol.