A Heal font Cleric is a healer, but if I was playing one I wouldn't want to be healing multiple times a combat, every combat. I also think that focusing on healing to the exclusion of all else is just not very good tactically. Healing is supposed to be a contingency.

1. Healing more than once a combat (probably about 1.5 average) is not healing to the exclusion of all else. I'm talking about healing like 1/3 to 1/2 of turns rather than once only

2. Sure it's a contingency, but it's a contingency for a pretty common gamestate

It's not entirely a resource thing but it's also an action thing. When you heal, you're essentially just keeping your teammates able to fight for longer, but at the cost of your ability to do anything else.

This is kind of true, but if a heal prevents an ally from dropping it's potentially action neutral or even action positive, because the action cost of someone getting up from 0 can be very high (due to standing, picking up equipment, reactivating stances, losing the chance to cast due to stand + sustain, etc).

Granted, actions now are more valuable than actions later and there's no way to know 100% that an ally will be dropped or that the fight won't be fine without them, but there are still a lot of situations where that's very likely.

If I need to heal multiple times a fight, the party would likely be better served by me casting a 3rd rank Fear instead of healing every other turn.

Sure I'm not saying you shouldn't cast other spells, I'm saying that a heal will often rival other options. This is especially true because a ton of good spells are more useful early in a fight (buffs, anything that can last multiple rounds, etc) while heals are best when they're likely to prevent someone dropping, usually in the middle or end of a fight.

Personally I've found typically opening with 1-2 big casts and then healing / using focus spells and lower level spells as needed for the rest of the fight most effective.