What is the difference between "year/month/day/minute by year/month/day/minute" and "year/month/day/minute after year/month/day/minute"?
According to my research, "year/month/day/minute after year/month/day/minute" seems to emphasize things (especially bad) happen repeatedly.
For example, "She hates doing the same work day after day.".
"year/month/day/minute after year/month/day/minute" seems to emphasize things (could be good or bad) happen a little at a time.
For example, "Day by day his condition improved.". and "Morale was sinking day by day.".