Nothing wrong with a date/description folder heirachy - unless that is your only organisation system.
However add keywords and then you can sort/find by any subject matter you want.
Folder organisation by subject matter is most certainly a complete waste of time as all images can be a multitude of subjects. Been there, done that and moved on.
Import and store everything by date as it's quick simple and easy and can be read/understood by any human, operating system or programme, LR can do this automatically. Once that is done add keywords and you can set up smart of dumb collections to collect your images by whatever criteria you want. These smart/dumb collections are the basics of how you can easily find your work in LR.
I agree with Jeremy's sentiments here.
Using a date-based folder organisation is an important fundamental building block for DAM.
I will also add shoot information after the date in naming the folder such as 2014-08-17_jack_jill_wedding or 2014-09-12_bondi_beach.
Images are renamed on import in a very similar way 2014-09-12_bondi_beach_0001.CR2 etc.
What this gives me are completely unambiguous filenames stored in folders that match the filenames.
Files are very unlikely to be inadvertently overwritten if they end up in another folder since they are unique and any file that is misplaced is easily noticed and the issue corrected.
However, we all agree here, that this arrangement does nothing to help with organising images in Lightroom.
This is where metadata and keywords are vital.
I will emphasise what Jeremy has already noted: folder-based systems are completely hopeless when trying to categorise images logically.
However, using keywords and metadata (this includes things such as ratings, ISO, lens used, labels etc etc), searches can be done and images found with common characteristics from anywhere in a particular catalog in Lightroom.
Although I do use the Library Filters on occasion to find and group images these are volatile and so I tend to create Smart collections that incorporate the characteristics that I want.
The advantage of Smart collections are manyfold but the two most useful are that they persist and also that any image, at any time that satisfies the inclusion criteria will become part of that Smart collection.
A single image can be included in as many Smart collections (or any other type of collection in Lightroom) as required without the need for any duplication of any image at file or folder level.
Inclusion in a collection is achieved by reference within the database (catalog).
So, in summary:
Although I pay a lot of attention to the folder structure of my image collection (the key characteristics for a folder structure include simplicity and scalability - hence the suggestion to use a date-based folder structure) I turn to keywords and metadata to organise images in Lightroom.
Tony Jay