The behavior you describe suggests that the person has a tendency towards circumstantial speech, where they tend to provide a lot of detail and information, but may struggle with organization or focus, leading to a rambling or scattered narrative. This type of speech pattern can be common in individuals with attention deficits or anxiety, who may struggle to regulate their thoughts and emotions while speaking.
When the person is in a comfortable and low-stress environment, they may be able to maintain their momentum and eventually arrive at a conclusion or point they are trying to make. However, if they become distracted or the environment becomes more stressful or challenging, they may lose their emotional “push,” which can cause their speech to slow down or become disjointed. This loss of momentum can be difficult to recover from, as the speaker may struggle to regain their emotional momentum or find their way back to their original train of thought.