In reading many Tuffy's reviews and experimenting with a variety of their toys, I think there are a few basic "rules": 1. Match the size/weight of the toy to the size/strength of the dog: The toy should be large-ish in terms of being able to fit inside the dog's mouth; the smaller the toy (or its parts), the easier to chew through quickly and successfully. And I have found that the heavier toys (e.g., stegosaurus, even Polly Pig) aren't as easy to haul around roughly. 2. As with most (if not all) chew toys, the dog should only have it under supervision. If s/he starts chewing through it, take it away and remind them to be gentle or redirect their attention for awhile. Letting them have the toy unsupervised for the entire day is just asking for the toy's destruction and, Heaven forbid, a choking or intestinal obstruction incident. 3. The toys with more of the heavy black trim and stitching seem to last better (e.g., lobster). No toy is indestructible; it's all a matter of degrees.
We have 3 rescued German Shorthaired Pointers (40 - 45 pound females) who are chewing queens: they quite literally EAT Kong toys and Tire-biter toys...eat them down to nubs. "How big is your Rottweiler?" they asked me at the pet store when I showed them a Kong that had been reduced to a mini-donut. So I wasn't sure what to expect with the Tuffy's.
Our first Polly Pig had the stuffing removed within a few days, and even though I kept re-stuffing her, they kept pulling it out. They love carrying around the empty carcass (still, after several months) and haven't been chewing on the remaining fabric. Apparently the fun is all in removing stuffing (and squeakers for the toys with those). Our second Polly Pig is completely intact; they carry her around but don't want to eviscerate her as they did with the first one.
The lobster has lasted extremely well. Our 2-year-old (who would have been an avid hunter) loves carrying it around in her mouth for hours at a time. A little chewing here and there, but mostly she treats it as a security blanket. Initially I was worried about all those little side arms, but since they are mostly thick, black edging and heavy stitching, they've held up surprisingly well. In fact, all are still on the toy after several months.
The stegosaurus was a huge hit with our 7-year-old for the first few days; she dragged it around with her, kept it from her sisters, and even pulled it onto the couch so she could sleep with her head on it But after a couple of weeks, she lost interest and now completely ignores it.
Howie the Horse had his tail and mane chewed off, as well as part of one ear. They then lost interest and left the rest of him intact.
Hilda the Hippo was the worst, in our experience. The fabric lining her mouth is very thin and in less than an hour, it had been chewed through and stuffing pulled out. Not durable at all. Too bad they didn't use the usual Tuffy's thick flannel material for her mouth. Hilda was a waste of money.
The yellow crab was popular, as it was easy to carry around. One claw (thick and puffy) was easily chewed through, but I put it up and out of reach when the dogs get too rough with it and only give it back a few days later as a "new toy" treat.
The 4-way ring, the bone-shape toys, and the oddball/footballs have stood up well; as good as new. The tug-o-war toy finally gave away in the middle (chewed part way through, stuffing removed, yet still attached), but they still play with the round ends.