Sending emails from different countries doesn’t mean you need to do several email spam tests. Doing an email spam test several times is very useful to iterate and try to improve your spam score. But it’s not related to sending emails from different countries. An email spam test should be done each time you change your email content (wording, links, images) and/or way of sending your emails (campaign sending tool, tracking domain, sending IP, domain, email address, etc.).