Big issue is the term "TTS"...Not everyone knows what their true size actually is, which creates even more confusion when someone recommends TTS or .5 up/down. Some people are between sizes too.
Trial and error is unfortunately what I've had to do on a lot of shoes across brands. So many times I've gone TTS and it fits too big, or sized down and it's been too small. Lost a lot of $$$ that way for sure. Personally if a shoe has excessive room in the toebox or has heel slip, or is too snug and crushing my toes I'm just not going to keep them. Got enough shoes that I need ones that don't fit me right.
What sucks is sometimes that's not even enough...After trial and error you think you've got your size for a particular model, then future colorways in that same model start fitting different depending on the materials used, change in mold, etc.
Anyways, all this talk of UA fitting TTS is making me sweat since I went down .5 lol. Mine are out for delivery today so will see soon...