While stardates meant nothing in universe (except in the Kelvin Timeline movies where the first 4 digits were the earth year), the TNG era shows were about 90% consistent, they tried to make sure each stardate for each following episode was a higher number than the last. It didn't always workout, but it did most of the time.
Out of universe, the second number of the stardate represented the season in TNG. For example, an episode of TNG with a stardate in the 41000 range is Season 1, 42000 is Season 2 etc.
At first the '4' stood for the 24th Century, but that rule was ignored in later seasons and shows. DS9 and Voyager however did keep up with the second number increasing after every season. Voyager season one was mostly in 48000, Season 2 49000, season 3 50000 etc.