Also worth noting that each congressperson only gets a certain amount of time to ask their questions, otherwise hearings could stretch pretty much indefinitely. So a hostile witness can run the clock out by rambling, while avoiding answering the questions they don’t want to answer. That’s why “reclaiming my time” is such a common thing to hear in these hearings: the congressperson is saying “they’re rambling instead of answering the question I asked, so I’m pausing my timer and reclaiming the wasted time they spent rambling.”