I believe that if one of them works, so Tor can realize that its network is not down, it will pick a new one rather soon.
if you don't tell tor which ports are blocked, and common ports (9001, 443, 80) are blocked, your Tor might not work at all.
Your anonymity can be influenced, too:
imagine there is one entry guard with orport 7777, and all other ports are blocked. Then tor will use that one (if it has cached consensus information)
that takes one hop of your path.