Our Cleric did use Spiritual Weapon quite a bit at levels 3 and 4. But what she found out is that many tougher combats are spread out ones against multiple foes. That's one of the reasons that they are tougher encounters. If we have an encounter with 2 or 3 separate groups of foes, Spiritual Weapon can easily have 1 or more rounds just being moved and not being used. At level 5, she used it at first, ran into the encounter with the Dragon (trying to add more damage) and the Dragon was all over the place. SW was used for a single round because the dragon was never close to it again. At that point, she stopped prepping it. Course, that was only "yesterday" in game time (2 sessions ago), so it's possible she'll use it again. But in her mind, I think it has lost a lot of its luster.
My encounters are not often smaller rooms where front lines can be formed and groups of foes can be AoEed (alternatively, the last fight the group was in was a maze of 5 foot wide corridors where PCs had to shoot ranged weapons past each other; in our game, that means a cover bonus and a chance to hit any intervening creatures).
So certain tactics that might work well cannot be done often. Sometimes they can, sometimes they cannot.
But healing in combat is something that rarely happens except for the tough fights. Even if a PC goes unconscious, they might not be healed with a spell if the fight is basically over.
As for Aid, we have many casters in our group. We have a Paladin (who often casts a second level Aid) and a Cleric (who often casts a third level Aid). Currently, we have something like 40 spells per day. Casting 2 spells at the beginning of the day is white noise. ~5% of the possible spells and it minimizes wasting actions for in combat healing. Definitely worth it. The more powerful Aid tends to go to the PCs who get damaged the most often / easiest, not necessarily the front line guys (who are rarely hit and have damage mitigation).
At higher levels, it makes even more sense to cast Aid when it becomes an even lower percentage of overall spells per day.
When it comes to Action Economy, I think that wasting full actions (as opposed to bonus actions) healing in combat is often a subpar tactic. Even using Aid as a third level spell (heal 10 for 3 PCs, total 30) is way subpar to Mass Healing Word (heal 4 to 9 for 6 PCs, total 24 to 54). In a big fight where everyone is injured and 2 PCs just went down, Mass Healing Word is just superior to the same level slot of Aid.