how can we restrict the maximum page size in a confluence page?

I'll second Nic's remarks Flavio. I have 8000 users and it's a lot about education. Also, potentially offer some solutions that are tailor-made for large attachments and they will probably prefer to use that instead of the effort of splitting files. For example, we have some power users using Box accounts and linking to the folder or files; one can also embed a Box folder on a page so they are still 'working in the wiki' but the files 'live' outside. Hope that helps.