Emma,
I took my vidaza on 5 consecutive days with the 7 day dose during those 5 days. Example if I was supposed to have 150mg per day for 7 days (total of 1050mg), I would instead have 210mg for 5 days. There are some studies that show different levels of effectiveness for the various regimens in use - 7 consecutive days, 5 days on 2 off, 2 on, and then the 5 day treatment that I had.
The following article gives some information, but there are many more studies than this one.
http://ascopubs.org/doi/full/10.1200/jco.2008.17.1058
I think the bottom line is that all three regimens can work for patients. Bailie is correct in stating that the 7 consecutive day regimen is what was approved by the FDA.
Hope this helps.