In column C I have the date, in column D I have the time, and in column E I
have a measurement taken at that date/time period. Theres 25,000+ rows of
this data, so doing what I need wouldnt be something easily done manually.

Based on the date and time, I would like to find the average of the
measurements taken per date, per shift. Dayshift is 7:00 AM until 9:00, and
nightshift is 9:01 PM until 6:59 AM.

I would like to post the results for each shift per date in column G at the
first two rows per date. There are about 200 rows per date, so where the
results would be about 200 rows apart.

Is there anyway this can be done?

Thanks in advance.