Apparently there's some vague timeline in Ranma 1/2.
The end of season four is (according to dialogue) two years after the beginning of the series, which conceivably means each season is about six months or so going by mathematical average.
SO WHY DO THEY NEVER MAKE IT OUT OF HIGH SCHOOL AFTER SEVEN FUCKING SEASONS?
Fuck you, long-running animated series and your disrespect for continuity.
Knights
It's like Dave's RAB, he's stated that they're in a continuous loop and no matter what they do, they'll be the as ever at the beginning of each episode.
Gendo
Damn you, time-hating fictional universes.