That's also been my experience. I have a researcher with a bit of skill in recycling and got two research missions, then the mentioned recycling mission, then another research mission. Either the research missions are too easy or the recycling missions way too expensive by comparison. I almost figured it was intentional, so you'd have to invest ~80k into completing the chain to get the reset.
You also need to consider that with the hippos and the other mobs in the zone you have a high chance for rare parts drops, which kind of factors into the reward.
Now someone correct me if I'm wrong, but the big hippos and bulls only spawn in F02, right? I found that you almost always have to take out the swampriders there and wait for respawn to get the quest-relevant mobs to spawn, which adds both to the time requirement and difficulty (especially for a non-le'd player).