Sussane - did they tell you specifically that the amount of sites was the reason your account was disabled? If not, it could be a lot of other issues.
i have 8 www.3atlat.com www.pro4all.net http://cn.pro4all.net http://fr.pro4all.net http://ar.pro4all.net http://es.pro4all.net http://de.pro4all.net http://it.pro4all.net http://ru.pro4all.net
I have 4 sites and try to make them qualitative and interesting. From the other hand a lot of my friends prefer making many sites in order to get profits from quantity...So you can choose...
Do you really think your ban was due to the number of sites? It seems most people have multiple sties. Could it be that Google might ban you if they think you're just throwing up useless sites only for AdSense (I'm not accusing, just a general question for everyone)? Right now I have just started. I've got two blogs going which I'm going to stick Adsense on very soon. I was thinking of making a lot of sites, but I'm good at writing and can crank out pages full of content so my plan isn't to make a bunch of useless sites.