My voucher from Modern States is different...

[mysonx3]

I hope it's just a thing where people weren't using them, and tracking for 6 months was problematic, so they decided to put an expiration date for scheduling the exam quickly.  I think that makes sense.

This is my guess. Seems like previously people could just grab all the vouchers even if they don't know if they'll need the test since they didn't expire.

That's a good thought. But come on, give a person more than 4 days....

Yeah, that seems a little short. But to be fair, there's no reason not to just go ahead and do it immediately. Of course, I could easily see somebody just not having the time during the four days immediately following the voucher being sent, which would be all sorts of frustrating for that person.