I’m about to re-launch a corporate website which has the same link structure for each of 10 different top level domains.
There are presently no other international websites, but there may be in the future.
For simplicity’s sake I intend to nominate a single primary domain and then use htaccess to redirect incoming traffic from alternative TLD’s back to the primary domain*
Is this best practice in terms of efficiency and SEO?
All depends on your content. If each site/tld has its own unique content for that region, then host this on its own domain.
If not don’t duplicate the site – redirect to a more ‘generic’ tld, like .com.