During the early 80's, CBC used to show Happy Days reruns during the after-school time slot in addition to first run episodes during prime time. CBC dropped the series after the 10th season and the final season aired in Canada via first-run syndication (I grew up in the Maritimes and I recall seeing final season Happy Days on regional network ATV as opposed to the private national network, CTV). After the series ended its run, CBC continued showing the series in the after-school slot until 1990 when it was replaced by Golden Girls reruns. Yet, when CBC would run through the series, they would stop at season nine and go back to season one. Was there a specific reason why that was? I watched every episode from season 1 through 9 dozens of times, but only ever got to see episodes 10 and 11 once and that was over 30 years ago. Did this happen when the reruns were shown in the US?

different syndication deals meant certain channels would only show groups of the seasons sometimes - a lot of times they would leave out the very early or very late seasons, probably because they werent as highly rated.

This may not help much as I've only been watching reruns since the early 2000s, but I've never come across a station or cable channel that didn't show the entire series.