I've just spent a couple of weeks in Taiwan - this verification happens every few minutes (iPhone) unless I constantly interact with this forum. Just stopping for a couple of minutes to read a post, or do something else, and the verification comes back.

Most of the time, after a few seconds, it verifies itself, but every few times it'll ask me to tick a box which somehow comprehensively proves I'm a real person.

Now I'm back in Europe, I'm getting this issue on my laptop (although I rarely need to tick the box). I don't understand why it can't be turned off for people logged in who have been members for a while, or at least whitelist an IP address for more than a few minutes.