There were 42 kids in my first grade class and half of them weren’t learning to read so the teacher had them chant the letter sounds every day while the rest of us did other work.
Half of the class had to be held back, but some of the rest of us started second grade reading at fifth grade level.
Hearing the later sounds in the background had made them sink no our brains.
For many years I had a home preschool and, while I did teach the kids the alphabet, I didn’t push them to learn. But every day at the beginning of nap time I’d play a phonics record or tape. (Yes, that was quite a while ago.)
Quite a few of the four year olds began reading on their own.
I call having kids hear the letter sounds in the background while they do other things “subliminal phonics.” It doesn’t work for all kids, but it can be a big advantage for some.