The problem with rapture is that it uses a lot of mana. Casting rapture plus five pw:shields uses 9300 mana. That is a lot of mana. If you are not using it selectively, then it will cause you to go oom pretty fast.
If you rarely cast smite that is really surprising. I heal in the range of 20-30 M+ a week on three disc priests. Most weeks I cast a ton of smite and actually try to do that. Smite is a super low mana cost heal. That is not to say I don’t use my other damaging spells, but if I am running Schism, I typically cast my other damage spells on CD and then Smite away–except for sitting on Mind Blast and Mind Games. Mind Blast uses a lot of mana–hence, I sit on it a lot. Mind Games, while doing a lot of damage, ideally ought to be used when the healing it does is going to be big–if you expect any in the near future. But I also like to use Mind Games with Schism to really pump damage.
That said, to say someone casts a spell too much or too little may be justified. But just from your two critiques here, I would say you are recommending a high mana use playstyle. While this may work for you, it may be because you are running with the same group–and you are getting a lot of chances to drink. If you heal a lot of different groups, though, you will quickly see wild swings in your use of spells and the healing you get from them. Some groups are literally fine with mostly atonement healing via your damage spells and a ton of smite. Other groups need a lot of raptures and/or even shadow mend spamming. The affixes will also change up what you need to do. Like last week–I healed about 20 dungeons with Grievous. I had no choice but to cast Shadow Mend a ton with some groups. In other cases the affix made no difference in my playstyle vs other affixes–because the players were using all of their buttons vs just their damage buttons–a relatively rare thing.
Disc is not the kind of healer like other healers where you just cast more of the same thing when the damage taken is a lot higher. Your spells and those you use depend on your sense of what is needed. If the damage is high and sustained you may need to be casting shadow mend a lot. On the other hand, if the group is using defensives, dodging, getting interrupts and even offhealing, the tank is great at mitigation and self-sustain generally, etc. then you are probably fine with doing a lot of damage and healing via atonement.
This may be fine in some cases, but in other cases you are going to risk pulling more mobs doing this. In other cases you are also going to risk taking avoidable damage doing this.
That said, it’s all food for thought. Disc is a tricky healer to master especially if you play with a lot of groups with varying skill levels. What works with one group will usually not work for another. But getting it right is the challenge.
You also made no mention of Mind Seer. I think it is one of the best spells to use whenever you can. It does a ton of damage.