There is no limit, as they are all separate applications and not done through UCAS. Individual countries may have their own application process which may limit the number of applications within that country (I think maybe Italy is like this? A national application scheme and you then rank universities in order of preference). Remember that if you are applying for medicine in the UK, only 4 of your 5 choices can be for medicine, and the 5th choice can either be left blank or used for another course, eg. some people chose to apply for biomedical science as well as a back-up.