Personally I think the traps make you feel good because you are able to see planaria caught, but they are still everywhere- even if unseen.
A while back when I had a planaria problem someone told me about planaria zero. I did some research and found it was not uncommon to have shrimp deaths from the use of it. This was one of my prized tanks with an unusual strain of cherries. I really couldn't afford to have any die.
So, after some more research, I found fenbendazole wouldn't hurt my shrimp. After some more research I found "fish bendazole" has a more active ingredient than just dog wormer (at least that's what I read) and it just made me feel better knowing it was for aquariums.
.1g per tenner. Mix in a cup of tank water and pour it in. Turn off light. Wait 3 days, and repeat if needed. Some people do a water change.
That simple, and worked great. None of my ramshorns died off. I took out my mystery as a precaution (and take any nerites out as well if you have any.)
I now have stocked up on this, and if hydra tag along to me from a shipment I use .05g. A nice low dose and over the next 3-4 days hydra disappears.
Hardly ever use it now, but nice to know it is there.