Six of one, or half-dozen of another, as my mom used to say. 30 days are 30 days. A full year’s course is gonna be 3 hours/day. It is compressed by definition. Whether the course has ‘finals’ after 15 days or midterms, the grade totals still count.
Our school district offers Frosh Bio, for example, over summer. While Bio 1A is not a separate course, with a final at the midpoint, instead the total scores at the end of 30 days counts as a double grade (for two semester’s worth).
I remember taking a whole year of US History in HS and that course was 3.5 hours/day (8:30 am to noon) for 30 days. We had weekly quizzes and a mid-term, but everyone understood that the class was “compressed” and every piece of work counted 2x. And yes, it required a “motivated person” to keep up.
And yes, it was impossible to take two full-year courses simultaneously. (Summer school was only offered in the morning.)
Since the course is online, what about searching for other online options. There are plenty available nowadays.