Each season was a little different with their "breaks" - like Victor said there is a month break between #11 and #12 (most likely for the holiday season). The structure back then for most shows was to show re-runs in the off weeks which really really didn't work for LOST being so serialized.
So they started tweaking the schedule for future seasons, including later start dates to keep a new show coming each week or doing a "pod" of 6 episodes (Season 3) in the fall, then taking a couple of months off and doing the other 16 episodes back to back to back in the spring. But each time I post the episode information like below it'll say the original air date so you'll get an idea of the timing.
Originally airing on November 17, 2004, 'Solitary' is Episode 9 of Season 1 of LOST.
It is the 9th episode overall and has an IMDB rating of 8.4, placing it as the #14 ranked episode of this season and #5 out of all the episodes shown so far.
Weird Magic
2023-10-30 18:42:04 +0000 UTC
You were wondering if this was the mid-season finale - No, there was an extra week between this episode and the next one (maybe due to the Thanksgiving holiday?) But the actual mid-season break was between episodes 11 and 12 - there was about one month between those two episodes.