Alternate folder structures on Import
Add the following two lines to your TranslatedStrings_Lr_en_US.txt file (include the quotes):
"$$$/AgImportDialog/ShootArrangement_5/Template=%Y/%m/%Y-%m-%d"
"$$$/AgImportDialog/ShootArrangement_5/Label=By date: 2005/12/2005-12-17"
Here's the location of TranslatedStrings.txt. If it doesn't exist, create it. Windows: C:\Program Files\Adobe\Adobe Lightroom\Resources\en\
How this works:
Lightroom uses the TranslatedStrings.txt mechanism for international localization – that is, this is how it changes text throughout the application for non-English languages. I've identified the strings used for the folder templates, and replaced them with my own. Other possibilities and permutations are possible – the Lua documentation contains the full set of date tags.
I also use the TranslatedStrings.txt mechanism to change the formats used to display pixel dimensions and f-stops throughout the application, mostly to make those strings a little narrower to save screen space.
This example replaces the third template, „2005/December 17“, with my own. I chose that one because I find it the most useless. I can't explain why the third one is number 5, but that's how they've done it.
Disclaimer:
The TranslatedStrings.txt mechanism is not fully supported by Adobe. They probably won't answer you if you ask them for help on it. This may not work in future versions of Lightroom. The file may be overwritten by updates, so save a copy elsewhere. Use of this trick may increase your risk of getting head lice or smelly feet.