If you're looking for actual stats of who is granted their requests this varies with each person. Sometimes requests are able to be granted and other times not. It also depends on how many 'wants' a person includes in their FAX.
If a person requests a room in the 70's section, room assigners have a lot of inventory to work with.
If a person requests a room on the upper floor in the 70's section with a tub and lake view there is far less inventory for room assigners to work with.
I really don't think we can accurately respond to 'have you gotten your requests each time they sent it at 5 days out' as it depends on how many requests are included in each persons fax.
Submitting a request via FAX or calling, at any time prior to your reservation, in no way guarantees your requests will be granted. Disney will do their best to grant your requests but it will depend on inventory available to them at the time they are assigning rooms.
The best thing to do is submit your request. The less restrictions you include, the more chance there is they can find a room that meets your request but there are no guarantees.