back when wood burning fireplaces and stoves etc were used to heat up homes during winter, the house was also closed up to prevent heat escaping, when summer came everything was washed including walls etc because it would get soot on it.
we have unfinished cleanup stuff, bunch of kids old toys in the garage, and car seats they are too big for, been asking friends to come take what they want, and then donate the rest.
I have to purge from my closet as well,
The biggest thing is the basement, there are boxes of stuff, in fall I gave away a bunch of books, old electronics, and comforters etc. have to finish that up.
biggest thing though is purging kids toys and clothes. thats one thing begum and I disagree on, I am fairly utilitarian when it comes to majority of kids clothes, she is not 
as far as hints go, I have not seen anyone clean as quickly and efficiently as my sister. think of the tasmanian devil going through the house and just cleaning..
she takes these big bins in each room, and throws things into, garbage, donate and goes somewhere else groups.
trash goes out right away, dontion stuff gets put in boxes right away, the goes somewhere else bin goes to guest room, then each room gets sorted. This way the unneeded stuff is out, the stuff that has to be in the room is put away properly, and then the goes somewhere else bin is tackled.
she does have a housekeeper who does laundry and scrubbing mopping etc. its a rather massive place, but 2 days its 100% done.