Sorry if this has been mentioned, but on the iPhone or iPad, go to your watched threads in Safari, tap the "share" button at the bottom (box with arrow pointing up), then tap "Add to Home Screen". Name it what you want, then boom. Instant access to your watched threads from the home screen, or whatever folder you want to put it in.
Android users can do the same, using the chrome browser. You simply tap the three dots up in the right hand corner and near the bottom of the menu list, you'll see "Add to home screen."
I still preferred having a dedicated app for TB but at least there are options. *shrug*