I started using a String Tracker about 20yrs ago because I did a lot of night hunting for pigs. The string definitely helped with recovering pigs in the dark!
About 15yrs ago I got on a lease in S.Tx that was mostly brush. There were few places to get off the ground in trees and most all of our sets were ground blinds. We started putting shoot thru netting in the windows (which I absolutely love), so I quit using the String Tracker because I figured there was no way it would work shooting thru the netting.
Fast forward to about 2yrs ago. I was on Trad Gang one day when a thread about using String Trackers came up. It was started by our very own Jerry Russell. I posted on that thread how I liked it, and used to use it, but that I had quit due to my blinds having netting in the windows. Shortly thereafter, I got a PM from Jerry telling me that the String Tracker worked fine when shooting thru netting, and even sent me a few videos of shots he had made thru netting.
This got my interest up again, and I went and dug my old String Tracker out. I custom made a little bracket so I could mount it to my longbow, and decided to try to shoot a pig thru the netting to see if it would work.
The next trip to the lease, I was ready. I ended up shooting the biggest hog (weight wise) that I have ever shot. The String Tracker worked great thru the netting, and I was once again hooked on using it.
Over the last two years I have shot quite a few pigs, deer, and turkeys with the String Tracker thru the netting. I doubt I will ever turkey hunt again without the String Tracker, as it has really upped my recovery rate on those tough birds!
I do believe that most critters will go a bit farther when a String Tracker is used. I don't know if that is because of the bit of added extra noise at the shot, or if it because of the string running thru the animal. or maybe a combination of both.
I also know this: After my recent experiences with the String Tracker, I firmly believe that there are a number of animals not recovered, that had good, lethal shots and bad blood trails! The string has saved my butt a couple times on dead critters where there was little to no blood trail to follow.
There are situations where the String Tracker is not a good choice also. Managing the string while stalking is almost impossible as it gets hung up on brush. Also, any set where you only have very tiny holes thru the brush would not be a good place for the String Tracker. And lastly, I have never shot mine over 20yds; almost all my hunting shots are 15yds or less. Logic tells me that gravity has to have an effect on it at some point, so I would think that any situation where you had to take very long shots would be a no-go for the String Tracker.
The String tracker will not save a bad shot, but it can surely save a bad blood trail on a good shot. I am convinced that it is an effective tool and will continue to use it to help me recover the animals I shoot!
Bisch