Some teachers of English have told students to “put in a comma when you think you need to take a breath”. In my darker moments, I think: “come the revolution, they’ll be first up against the wall.”
In the current phase space of all of possible rules applicable to the use of the comma in English, breathing is an expired option.*
A comma is another one of those typesetters’ marks intended to break long-winded ideas up into manageable units of meaning. It’s an aid to comprehension, not breathing.
Guidance on using commas has to start with considering two contrasting ideas. The first is the idea of separation. The second, quite counterintuitively, is the idea of joining together.
Let’s think about these ideas. If you use a comma to make a list of things, does your particular mindset suggest that you are separating the items, or joining them together in a list? Whichever you choose, you do have to acknowledge that its opposite is a valid point of view. In any case, it seems that supporters of the “joining together” school of thought got to make the rule about what happens at the end of a list, where if you use the word and before the last item, you’re not allowed to use a comma: the basis for this is that you should not use two conjunctions together because you don’t need to join things together twice. Or is it separate them twice? And does that mean that a conjunction can also separate things?
It’s a short step from a list of single things to imagining a list of ideas made up of multiple words each, which is what happens in a sentence. That leads us to think about the rules governing the use of commas within sentences. Whatever the details of the comma rules are, the ideas of separation and joining together are at the heart of what you do.
* But if you insist on perpetuating this calumny, look at Comma, history for a potted intellectual justification of your prejudice.