It turns out Republicans are using their time with witnesses exactly as you'd expect them to:
Republican lawmakers have used the congressional impeachment inquiry to gather information on a CIA employee who filed a whistleblower complaint, press witnesses on their loyalty to President Trump and advance conspiratorial claims that Ukraine was involved in the 2016 election, according to current and former officials involved in the proceedings.
GOP members and staffers have repeatedly raised the name of a person suspected of filing the whistleblower complaint that exposed Trump’s effort to pressure Ukraine to conduct investigations into his political adversaries, officials said.
. . . As a result, Democrats contend that Republicans are not using the inquiry to uncover facts about the administration’s interactions with Ukraine. “There’s been zero interest [among the GOP] in actually getting to the conduct of the president,” a Democratic lawmaker said. “It’s not the subject of their questioning at all.”
. . . Republicans appear to be trying to link their concerns about the Steele dossier to Ukraine, a country Trump has said, without evidence, interfered in the election. One Democratic official present for witness testimony said Republicans were asking witnesses things like, “Are you aware that part of the evidence in the Steele Dossier originated in Ukraine?”
“The witnesses are like, ‘I have no idea what you’re talking about,’ which makes sense, because it’s totally made up,” an official said.
. . . Republicans have also used their time to go after Biden, including citing Trump’s unsubstantiated allegation that Biden used his position as vice president to pressure Ukraine to fire a prosecutor who had been investigating the energy company that had employed Biden’s son. During an interview with George Kent, the deputy assistant secretary of state responsible for Ukraine, GOP questioners repeatedly asked the diplomat whether the United States had led the effort to remove the Ukrainian prosecutor, Viktor Shokin.
U.S. officials did press for Shokin’s removal amid concerns that he was allowing corruption to go unchecked in Ukraine, a position backed at the time by U.S. allies in Europe.
But for bad faith bullshit, Republicans have defense of Trump at all.