What are the patterns to spell distribution across classes?


It is obvious that there are patterns to spell distribution across classes.

For instance, typically only druids and rangers have access to nature-themed spells. As another example, healing spells tend toward cleric and away from wizard, if that makes sense.

There are some surprises. For instance, Cure Wounds is available to bard, cleric, druid, paladin, and ranger; whereas Healing Word is available to only bard, cleric, and druid.

Another somewhat surprising example: Find Familiar is only available to wizard. Why is that? Certainly the general tropes of fantasy don’t suggest clerics would have familiars, but what about sorcerers and warlocks?

Clearly there are patterns. In the case of Cure Wounds and Healing Word, the pattern could be that only full casters get to heal at a distance; or, perhaps healing by touch is more thematically appropriate for paladins and rangers.

The Question

Is there any published official material stating, as the title says, What the patterns are to spell distribution across classes?

Failing published official material, is there any published unofficial material on the question, or any third party analysis?

I’m not looking for answers about my specific examples, but about the overall picture.

I’ve looked through the published materials, the internet generally, and particularly here on rpg, and haven’t found anything, but maybe I’m just not looking in the right place.