ホモテナシ

本仕舞い in the following cases:

• room smaller than 4.5 畳
• 棚 or 長板 is used
• 花月の式（かげつ）
• more formal 点前: 貴人 or 荘（かざり）

• Ulrich explained this really well: If it's outer 炉 corner in 炉, it's 本じまえ; if it's inner corner, it's 中じまい.
• If the room is 4.5 mats or larger, it depends on the 点前, if it's smaller, it's always the inner corner and always 本じまい.
• Hiromi added to this VI 22 that you can also memorise it like this: If you can use one hand to move the 茶碗, you can do 中じまい (technically, you could move it with one hand for 茶入飾 etc, but they are on the same level as 茶碗飾, so that's that).
• She explained further that 本仕舞 is the 'proper way', because things go back to whence they came; and 中仕舞い is the 'informal', or 侘び way, because we allow for this imperfection 😍 Because of this, we compensate the small room's 侘び-ness by finishing 本仕舞い; and tone down the large room's style by sometimes finishing 中仕舞い.

is this by any chance the latter 8 of 子習い?

Also, 長板 and 台子 close 本じまい; and for 運び, it seems you can choose (if you are in a 4.5 mat room, obviously). Also, 四ヵ伝 are 本仕舞.