Ideally you want them to not be connected. If they have different public contact info/details, then in theory Google won't know they're all connected, so (again, in theory) they might have the same value as if they were separate web 2.0s.
However, if they're all from the same account and you spam one of them into oblivion, then Wordpress/Joomla/Jimdo/whatever might ban them all. Also, you generally get diminishing returns as you make more and more links from the same domain. One good Wordpress web 2.0 + one good Weebly web 2.0 + one good Joomla web 2.0 is generally a better idea than ten shitty web 2.0s all on Weebly (or whatever).
Consider reading these:
Web 2.0 Creation
- https://www.blackhatworld.com/seo/my-super-web-2-0-plan.823190/
- https://www.blackhatworld.com/seo/guide-the-art-of-super-web-2-0-creation.683979/
- https://www.gotchseo.com/the-super-web-2-0/
Also, since it seems like you may be fairly new, here is the rest of my list of general recommended threads that may be useful to you:
https://www.blackhatworld.com/seo/best-seo-smm-web-2-0-guide-public-excerpts-from-our-internal-marketing-guide.953359/#post-10196243