A good teacher in a school will also break up phonics instruction and weave it in throughout the day. The challenge of giving individual instruction to 20-35 students is monumental, though. Source: I'm a kindergarten and first grade teacher.
You teach 30+ first graders solo? Each kid would get 2 minutes an hour. A close to impossible teaching task. Is that a normal teacher student ratio in your district? Is that normal for public school?
Looking around in the US[1], it looks like legally the cap can be from 1:15 - 1:25 (K-3). It looks like 1/3 of states don't have any legal cap. Funny enough, this chart[2] correlating reading performance and class size stops at 1:21 for 4th and 8th grade.
