Questions 1 and 2: you're right, this a central challenge for theories of stuttering, including this one, based around auditory processing. Another example often raised is, why would we block at the beginning of a sentence, before auditory feedback has started? Most auditory-based theories (like [Civier et al. 2010](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2939043/#S22title)) just say that their theory doesn't explain silent types of stuttering. The author of this study also acknowledges this problem in the [discussion](https://www.sciencedirect.com/science/article/pii/S0306987723001627#s0035), but offers the possibility that stuttering could "triggered by the anticipation of stuttering... as the cerebellum’s response to an anticipated error." I think this really results in 2 theories of stuttering: an auditory-based one (described in this paper) which causes repetitions and prolongations, and an anticipation based one (described by [other authors](https://sci-hub.ru/https://www.sciencedirect.com/science/article/abs/pii/S0094730X1500025X?casa_token=6lFS_Uo82rsAAAAA:S46JMPD1raLm9a6lMf_f47BJf1AySZi7Ugk1k4kWgJTQMslvcrBsoOg2qoe262TgNVcYXNmiGbE#bib0490)) that causes silent blocks of the kind you mention. ​ Question 3: this paper doesn't describe specific types of perceived errors, but I imagine that they would be errors which would cause any speaker to repeat themselves. For example, when speaking to someone named "Bob", accidentally starting to pronounce their name as "Dob" would cause the speaker go back and try to say the name again correctly. As mentioned above though, I don't think that this perceptual error alone would lead to a 60-second block.