Assuming you clear 4 enemies per round. 4*7 = 28 enemies per set. 1000/28 = 35.7... That's a little more than 35 rounds. I believe there are 10 days for tempest trials+. If you only did it 3 times a day, you'd only be doing 30 rounds. It's likely that you'll be going against maps of 5 foes than 3 foes, but still, it's not guaranteed you'll defeat 1,000 enemies even if you reach 50,000. What a sham. And for 1 Orb.

To put it in perspective, it takes 15 stamina per run. 15*35 = 525 stamina. 525 * 5mins = 2625mins of waiting. 2625/60 = 43.75 hours of waiting if you weren't using any stamina pots. Again, for 1 Orb. What a fucking piece of shit of an anniversary.