Disc 2 of every Season

I have been watching all of SG-1 (and Atlantis) straight through on DVD. I'm in the middle of Season 10 now and after finishing the 2nd disc last night I began wondering if anyone else had noticed or if it was just me but it seems that the 2nd disk of EVERY season has the worst episodes, or at least the stand alone episodes that do not move the overall story along. All of my least favorite episodes throughout the entire series and carrying over into Atlantis are episodes 5-8 of each season. So I actually have two thoughts here: 1.) Has anyone else noticed this trend? and 2.) Does this trend carry over into other shows and if so is there a reason behind it?

Now I am not a media student but I do have a couple theories myself. My main theory is that these episodes typically air around the holiday season and they don't want to air episodes that move the story along b/c it is the time when there are the least amount of viewers. Can anyone confirm or deny this?