Hi,
I can't say much to your question as I have never done this. But I have been on and off microgynon / levest for years. (They are both the same combined pill they are just called different names due to the manufacturer, I think).
I was just wondering why do you take three packets in a row then have a 4 day break? Did your prescriber say you could do this? (curious)
(I have always taken my pills as 21 days on pills and 7 days off pills and I have never had any real problems except for bad nausea for the first 2 days of each pack - usually in the mornings)